1 // SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
2 /* Copyright (c) 2018 Facebook */
3
4 #include <byteswap.h>
5 #include <endian.h>
6 #include <stdio.h>
7 #include <stdlib.h>
8 #include <string.h>
9 #include <fcntl.h>
10 #include <unistd.h>
11 #include <errno.h>
12 #include <sys/utsname.h>
13 #include <sys/param.h>
14 #include <sys/stat.h>
15 #include <linux/kernel.h>
16 #include <linux/err.h>
17 #include <linux/btf.h>
18 #include <gelf.h>
19 #include "btf.h"
20 #include "bpf.h"
21 #include "libbpf.h"
22 #include "libbpf_internal.h"
23 #include "hashmap.h"
24 #include "strset.h"
25
26 #define BTF_MAX_NR_TYPES 0x7fffffffU
27 #define BTF_MAX_STR_OFFSET 0x7fffffffU
28
29 static struct btf_type btf_void;
30
31 struct btf {
32 /* raw BTF data in native endianness */
33 void *raw_data;
34 /* raw BTF data in non-native endianness */
35 void *raw_data_swapped;
36 __u32 raw_size;
37 /* whether target endianness differs from the native one */
38 bool swapped_endian;
39
40 /*
41 * When BTF is loaded from an ELF or raw memory it is stored
42 * in a contiguous memory block. The hdr, type_data, and, strs_data
43 * point inside that memory region to their respective parts of BTF
44 * representation:
45 *
46 * +--------------------------------+
47 * | Header | Types | Strings |
48 * +--------------------------------+
49 * ^ ^ ^
50 * | | |
51 * hdr | |
52 * types_data-+ |
53 * strs_data------------+
54 *
55 * If BTF data is later modified, e.g., due to types added or
56 * removed, BTF deduplication performed, etc, this contiguous
57 * representation is broken up into three independently allocated
58 * memory regions to be able to modify them independently.
59 * raw_data is nulled out at that point, but can be later allocated
60 * and cached again if user calls btf__get_raw_data(), at which point
61 * raw_data will contain a contiguous copy of header, types, and
62 * strings:
63 *
64 * +----------+ +---------+ +-----------+
65 * | Header | | Types | | Strings |
66 * +----------+ +---------+ +-----------+
67 * ^ ^ ^
68 * | | |
69 * hdr | |
70 * types_data----+ |
71 * strset__data(strs_set)-----+
72 *
73 * +----------+---------+-----------+
74 * | Header | Types | Strings |
75 * raw_data----->+----------+---------+-----------+
76 */
77 struct btf_header *hdr;
78
79 void *types_data;
80 size_t types_data_cap; /* used size stored in hdr->type_len */
81
82 /* type ID to `struct btf_type *` lookup index
83 * type_offs[0] corresponds to the first non-VOID type:
84 * - for base BTF it's type [1];
85 * - for split BTF it's the first non-base BTF type.
86 */
87 __u32 *type_offs;
88 size_t type_offs_cap;
89 /* number of types in this BTF instance:
90 * - doesn't include special [0] void type;
91 * - for split BTF counts number of types added on top of base BTF.
92 */
93 __u32 nr_types;
94 /* if not NULL, points to the base BTF on top of which the current
95 * split BTF is based
96 */
97 struct btf *base_btf;
98 /* BTF type ID of the first type in this BTF instance:
99 * - for base BTF it's equal to 1;
100 * - for split BTF it's equal to biggest type ID of base BTF plus 1.
101 */
102 int start_id;
103 /* logical string offset of this BTF instance:
104 * - for base BTF it's equal to 0;
105 * - for split BTF it's equal to total size of base BTF's string section size.
106 */
107 int start_str_off;
108
109 /* only one of strs_data or strs_set can be non-NULL, depending on
110 * whether BTF is in a modifiable state (strs_set is used) or not
111 * (strs_data points inside raw_data)
112 */
113 void *strs_data;
114 /* a set of unique strings */
115 struct strset *strs_set;
116 /* whether strings are already deduplicated */
117 bool strs_deduped;
118
119 /* BTF object FD, if loaded into kernel */
120 int fd;
121
122 /* Pointer size (in bytes) for a target architecture of this BTF */
123 int ptr_sz;
124 };
125
ptr_to_u64(const void * ptr)126 static inline __u64 ptr_to_u64(const void *ptr)
127 {
128 return (__u64) (unsigned long) ptr;
129 }
130
131 /* Ensure given dynamically allocated memory region pointed to by *data* with
132 * capacity of *cap_cnt* elements each taking *elem_sz* bytes has enough
133 * memory to accomodate *add_cnt* new elements, assuming *cur_cnt* elements
134 * are already used. At most *max_cnt* elements can be ever allocated.
135 * If necessary, memory is reallocated and all existing data is copied over,
136 * new pointer to the memory region is stored at *data, new memory region
137 * capacity (in number of elements) is stored in *cap.
138 * On success, memory pointer to the beginning of unused memory is returned.
139 * On error, NULL is returned.
140 */
libbpf_add_mem(void ** data,size_t * cap_cnt,size_t elem_sz,size_t cur_cnt,size_t max_cnt,size_t add_cnt)141 void *libbpf_add_mem(void **data, size_t *cap_cnt, size_t elem_sz,
142 size_t cur_cnt, size_t max_cnt, size_t add_cnt)
143 {
144 size_t new_cnt;
145 void *new_data;
146
147 if (cur_cnt + add_cnt <= *cap_cnt)
148 return *data + cur_cnt * elem_sz;
149
150 /* requested more than the set limit */
151 if (cur_cnt + add_cnt > max_cnt)
152 return NULL;
153
154 new_cnt = *cap_cnt;
155 new_cnt += new_cnt / 4; /* expand by 25% */
156 if (new_cnt < 16) /* but at least 16 elements */
157 new_cnt = 16;
158 if (new_cnt > max_cnt) /* but not exceeding a set limit */
159 new_cnt = max_cnt;
160 if (new_cnt < cur_cnt + add_cnt) /* also ensure we have enough memory */
161 new_cnt = cur_cnt + add_cnt;
162
163 new_data = libbpf_reallocarray(*data, new_cnt, elem_sz);
164 if (!new_data)
165 return NULL;
166
167 /* zero out newly allocated portion of memory */
168 memset(new_data + (*cap_cnt) * elem_sz, 0, (new_cnt - *cap_cnt) * elem_sz);
169
170 *data = new_data;
171 *cap_cnt = new_cnt;
172 return new_data + cur_cnt * elem_sz;
173 }
174
175 /* Ensure given dynamically allocated memory region has enough allocated space
176 * to accommodate *need_cnt* elements of size *elem_sz* bytes each
177 */
libbpf_ensure_mem(void ** data,size_t * cap_cnt,size_t elem_sz,size_t need_cnt)178 int libbpf_ensure_mem(void **data, size_t *cap_cnt, size_t elem_sz, size_t need_cnt)
179 {
180 void *p;
181
182 if (need_cnt <= *cap_cnt)
183 return 0;
184
185 p = libbpf_add_mem(data, cap_cnt, elem_sz, *cap_cnt, SIZE_MAX, need_cnt - *cap_cnt);
186 if (!p)
187 return -ENOMEM;
188
189 return 0;
190 }
191
btf_add_type_idx_entry(struct btf * btf,__u32 type_off)192 static int btf_add_type_idx_entry(struct btf *btf, __u32 type_off)
193 {
194 __u32 *p;
195
196 p = libbpf_add_mem((void **)&btf->type_offs, &btf->type_offs_cap, sizeof(__u32),
197 btf->nr_types, BTF_MAX_NR_TYPES, 1);
198 if (!p)
199 return -ENOMEM;
200
201 *p = type_off;
202 return 0;
203 }
204
btf_bswap_hdr(struct btf_header * h)205 static void btf_bswap_hdr(struct btf_header *h)
206 {
207 h->magic = bswap_16(h->magic);
208 h->hdr_len = bswap_32(h->hdr_len);
209 h->type_off = bswap_32(h->type_off);
210 h->type_len = bswap_32(h->type_len);
211 h->str_off = bswap_32(h->str_off);
212 h->str_len = bswap_32(h->str_len);
213 }
214
btf_parse_hdr(struct btf * btf)215 static int btf_parse_hdr(struct btf *btf)
216 {
217 struct btf_header *hdr = btf->hdr;
218 __u32 meta_left;
219
220 if (btf->raw_size < sizeof(struct btf_header)) {
221 pr_debug("BTF header not found\n");
222 return -EINVAL;
223 }
224
225 if (hdr->magic == bswap_16(BTF_MAGIC)) {
226 btf->swapped_endian = true;
227 if (bswap_32(hdr->hdr_len) != sizeof(struct btf_header)) {
228 pr_warn("Can't load BTF with non-native endianness due to unsupported header length %u\n",
229 bswap_32(hdr->hdr_len));
230 return -ENOTSUP;
231 }
232 btf_bswap_hdr(hdr);
233 } else if (hdr->magic != BTF_MAGIC) {
234 pr_debug("Invalid BTF magic:%x\n", hdr->magic);
235 return -EINVAL;
236 }
237
238 meta_left = btf->raw_size - sizeof(*hdr);
239 if (meta_left < hdr->str_off + hdr->str_len) {
240 pr_debug("Invalid BTF total size:%u\n", btf->raw_size);
241 return -EINVAL;
242 }
243
244 if (hdr->type_off + hdr->type_len > hdr->str_off) {
245 pr_debug("Invalid BTF data sections layout: type data at %u + %u, strings data at %u + %u\n",
246 hdr->type_off, hdr->type_len, hdr->str_off, hdr->str_len);
247 return -EINVAL;
248 }
249
250 if (hdr->type_off % 4) {
251 pr_debug("BTF type section is not aligned to 4 bytes\n");
252 return -EINVAL;
253 }
254
255 return 0;
256 }
257
btf_parse_str_sec(struct btf * btf)258 static int btf_parse_str_sec(struct btf *btf)
259 {
260 const struct btf_header *hdr = btf->hdr;
261 const char *start = btf->strs_data;
262 const char *end = start + btf->hdr->str_len;
263
264 if (btf->base_btf && hdr->str_len == 0)
265 return 0;
266 if (!hdr->str_len || hdr->str_len - 1 > BTF_MAX_STR_OFFSET || end[-1]) {
267 pr_debug("Invalid BTF string section\n");
268 return -EINVAL;
269 }
270 if (!btf->base_btf && start[0]) {
271 pr_debug("Invalid BTF string section\n");
272 return -EINVAL;
273 }
274 return 0;
275 }
276
btf_type_size(const struct btf_type * t)277 static int btf_type_size(const struct btf_type *t)
278 {
279 const int base_size = sizeof(struct btf_type);
280 __u16 vlen = btf_vlen(t);
281
282 switch (btf_kind(t)) {
283 case BTF_KIND_FWD:
284 case BTF_KIND_CONST:
285 case BTF_KIND_VOLATILE:
286 case BTF_KIND_RESTRICT:
287 case BTF_KIND_PTR:
288 case BTF_KIND_TYPEDEF:
289 case BTF_KIND_FUNC:
290 case BTF_KIND_FLOAT:
291 return base_size;
292 case BTF_KIND_INT:
293 return base_size + sizeof(__u32);
294 case BTF_KIND_ENUM:
295 return base_size + vlen * sizeof(struct btf_enum);
296 case BTF_KIND_ARRAY:
297 return base_size + sizeof(struct btf_array);
298 case BTF_KIND_STRUCT:
299 case BTF_KIND_UNION:
300 return base_size + vlen * sizeof(struct btf_member);
301 case BTF_KIND_FUNC_PROTO:
302 return base_size + vlen * sizeof(struct btf_param);
303 case BTF_KIND_VAR:
304 return base_size + sizeof(struct btf_var);
305 case BTF_KIND_DATASEC:
306 return base_size + vlen * sizeof(struct btf_var_secinfo);
307 default:
308 pr_debug("Unsupported BTF_KIND:%u\n", btf_kind(t));
309 return -EINVAL;
310 }
311 }
312
btf_bswap_type_base(struct btf_type * t)313 static void btf_bswap_type_base(struct btf_type *t)
314 {
315 t->name_off = bswap_32(t->name_off);
316 t->info = bswap_32(t->info);
317 t->type = bswap_32(t->type);
318 }
319
btf_bswap_type_rest(struct btf_type * t)320 static int btf_bswap_type_rest(struct btf_type *t)
321 {
322 struct btf_var_secinfo *v;
323 struct btf_member *m;
324 struct btf_array *a;
325 struct btf_param *p;
326 struct btf_enum *e;
327 __u16 vlen = btf_vlen(t);
328 int i;
329
330 switch (btf_kind(t)) {
331 case BTF_KIND_FWD:
332 case BTF_KIND_CONST:
333 case BTF_KIND_VOLATILE:
334 case BTF_KIND_RESTRICT:
335 case BTF_KIND_PTR:
336 case BTF_KIND_TYPEDEF:
337 case BTF_KIND_FUNC:
338 case BTF_KIND_FLOAT:
339 return 0;
340 case BTF_KIND_INT:
341 *(__u32 *)(t + 1) = bswap_32(*(__u32 *)(t + 1));
342 return 0;
343 case BTF_KIND_ENUM:
344 for (i = 0, e = btf_enum(t); i < vlen; i++, e++) {
345 e->name_off = bswap_32(e->name_off);
346 e->val = bswap_32(e->val);
347 }
348 return 0;
349 case BTF_KIND_ARRAY:
350 a = btf_array(t);
351 a->type = bswap_32(a->type);
352 a->index_type = bswap_32(a->index_type);
353 a->nelems = bswap_32(a->nelems);
354 return 0;
355 case BTF_KIND_STRUCT:
356 case BTF_KIND_UNION:
357 for (i = 0, m = btf_members(t); i < vlen; i++, m++) {
358 m->name_off = bswap_32(m->name_off);
359 m->type = bswap_32(m->type);
360 m->offset = bswap_32(m->offset);
361 }
362 return 0;
363 case BTF_KIND_FUNC_PROTO:
364 for (i = 0, p = btf_params(t); i < vlen; i++, p++) {
365 p->name_off = bswap_32(p->name_off);
366 p->type = bswap_32(p->type);
367 }
368 return 0;
369 case BTF_KIND_VAR:
370 btf_var(t)->linkage = bswap_32(btf_var(t)->linkage);
371 return 0;
372 case BTF_KIND_DATASEC:
373 for (i = 0, v = btf_var_secinfos(t); i < vlen; i++, v++) {
374 v->type = bswap_32(v->type);
375 v->offset = bswap_32(v->offset);
376 v->size = bswap_32(v->size);
377 }
378 return 0;
379 default:
380 pr_debug("Unsupported BTF_KIND:%u\n", btf_kind(t));
381 return -EINVAL;
382 }
383 }
384
btf_parse_type_sec(struct btf * btf)385 static int btf_parse_type_sec(struct btf *btf)
386 {
387 struct btf_header *hdr = btf->hdr;
388 void *next_type = btf->types_data;
389 void *end_type = next_type + hdr->type_len;
390 int err, type_size;
391
392 while (next_type + sizeof(struct btf_type) <= end_type) {
393 if (btf->swapped_endian)
394 btf_bswap_type_base(next_type);
395
396 type_size = btf_type_size(next_type);
397 if (type_size < 0)
398 return type_size;
399 if (next_type + type_size > end_type) {
400 pr_warn("BTF type [%d] is malformed\n", btf->start_id + btf->nr_types);
401 return -EINVAL;
402 }
403
404 if (btf->swapped_endian && btf_bswap_type_rest(next_type))
405 return -EINVAL;
406
407 err = btf_add_type_idx_entry(btf, next_type - btf->types_data);
408 if (err)
409 return err;
410
411 next_type += type_size;
412 btf->nr_types++;
413 }
414
415 if (next_type != end_type) {
416 pr_warn("BTF types data is malformed\n");
417 return -EINVAL;
418 }
419
420 return 0;
421 }
422
btf__get_nr_types(const struct btf * btf)423 __u32 btf__get_nr_types(const struct btf *btf)
424 {
425 return btf->start_id + btf->nr_types - 1;
426 }
427
btf__base_btf(const struct btf * btf)428 const struct btf *btf__base_btf(const struct btf *btf)
429 {
430 return btf->base_btf;
431 }
432
433 /* internal helper returning non-const pointer to a type */
btf_type_by_id(struct btf * btf,__u32 type_id)434 struct btf_type *btf_type_by_id(struct btf *btf, __u32 type_id)
435 {
436 if (type_id == 0)
437 return &btf_void;
438 if (type_id < btf->start_id)
439 return btf_type_by_id(btf->base_btf, type_id);
440 return btf->types_data + btf->type_offs[type_id - btf->start_id];
441 }
442
btf__type_by_id(const struct btf * btf,__u32 type_id)443 const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 type_id)
444 {
445 if (type_id >= btf->start_id + btf->nr_types)
446 return NULL;
447 return btf_type_by_id((struct btf *)btf, type_id);
448 }
449
determine_ptr_size(const struct btf * btf)450 static int determine_ptr_size(const struct btf *btf)
451 {
452 const struct btf_type *t;
453 const char *name;
454 int i, n;
455
456 if (btf->base_btf && btf->base_btf->ptr_sz > 0)
457 return btf->base_btf->ptr_sz;
458
459 n = btf__get_nr_types(btf);
460 for (i = 1; i <= n; i++) {
461 t = btf__type_by_id(btf, i);
462 if (!btf_is_int(t))
463 continue;
464
465 name = btf__name_by_offset(btf, t->name_off);
466 if (!name)
467 continue;
468
469 if (strcmp(name, "long int") == 0 ||
470 strcmp(name, "long unsigned int") == 0) {
471 if (t->size != 4 && t->size != 8)
472 continue;
473 return t->size;
474 }
475 }
476
477 return -1;
478 }
479
btf_ptr_sz(const struct btf * btf)480 static size_t btf_ptr_sz(const struct btf *btf)
481 {
482 if (!btf->ptr_sz)
483 ((struct btf *)btf)->ptr_sz = determine_ptr_size(btf);
484 return btf->ptr_sz < 0 ? sizeof(void *) : btf->ptr_sz;
485 }
486
487 /* Return pointer size this BTF instance assumes. The size is heuristically
488 * determined by looking for 'long' or 'unsigned long' integer type and
489 * recording its size in bytes. If BTF type information doesn't have any such
490 * type, this function returns 0. In the latter case, native architecture's
491 * pointer size is assumed, so will be either 4 or 8, depending on
492 * architecture that libbpf was compiled for. It's possible to override
493 * guessed value by using btf__set_pointer_size() API.
494 */
btf__pointer_size(const struct btf * btf)495 size_t btf__pointer_size(const struct btf *btf)
496 {
497 if (!btf->ptr_sz)
498 ((struct btf *)btf)->ptr_sz = determine_ptr_size(btf);
499
500 if (btf->ptr_sz < 0)
501 /* not enough BTF type info to guess */
502 return 0;
503
504 return btf->ptr_sz;
505 }
506
507 /* Override or set pointer size in bytes. Only values of 4 and 8 are
508 * supported.
509 */
btf__set_pointer_size(struct btf * btf,size_t ptr_sz)510 int btf__set_pointer_size(struct btf *btf, size_t ptr_sz)
511 {
512 if (ptr_sz != 4 && ptr_sz != 8)
513 return -EINVAL;
514 btf->ptr_sz = ptr_sz;
515 return 0;
516 }
517
is_host_big_endian(void)518 static bool is_host_big_endian(void)
519 {
520 #if __BYTE_ORDER == __LITTLE_ENDIAN
521 return false;
522 #elif __BYTE_ORDER == __BIG_ENDIAN
523 return true;
524 #else
525 # error "Unrecognized __BYTE_ORDER__"
526 #endif
527 }
528
btf__endianness(const struct btf * btf)529 enum btf_endianness btf__endianness(const struct btf *btf)
530 {
531 if (is_host_big_endian())
532 return btf->swapped_endian ? BTF_LITTLE_ENDIAN : BTF_BIG_ENDIAN;
533 else
534 return btf->swapped_endian ? BTF_BIG_ENDIAN : BTF_LITTLE_ENDIAN;
535 }
536
btf__set_endianness(struct btf * btf,enum btf_endianness endian)537 int btf__set_endianness(struct btf *btf, enum btf_endianness endian)
538 {
539 if (endian != BTF_LITTLE_ENDIAN && endian != BTF_BIG_ENDIAN)
540 return -EINVAL;
541
542 btf->swapped_endian = is_host_big_endian() != (endian == BTF_BIG_ENDIAN);
543 if (!btf->swapped_endian) {
544 free(btf->raw_data_swapped);
545 btf->raw_data_swapped = NULL;
546 }
547 return 0;
548 }
549
btf_type_is_void(const struct btf_type * t)550 static bool btf_type_is_void(const struct btf_type *t)
551 {
552 return t == &btf_void || btf_is_fwd(t);
553 }
554
btf_type_is_void_or_null(const struct btf_type * t)555 static bool btf_type_is_void_or_null(const struct btf_type *t)
556 {
557 return !t || btf_type_is_void(t);
558 }
559
560 #define MAX_RESOLVE_DEPTH 32
561
btf__resolve_size(const struct btf * btf,__u32 type_id)562 __s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
563 {
564 const struct btf_array *array;
565 const struct btf_type *t;
566 __u32 nelems = 1;
567 __s64 size = -1;
568 int i;
569
570 t = btf__type_by_id(btf, type_id);
571 for (i = 0; i < MAX_RESOLVE_DEPTH && !btf_type_is_void_or_null(t);
572 i++) {
573 switch (btf_kind(t)) {
574 case BTF_KIND_INT:
575 case BTF_KIND_STRUCT:
576 case BTF_KIND_UNION:
577 case BTF_KIND_ENUM:
578 case BTF_KIND_DATASEC:
579 case BTF_KIND_FLOAT:
580 size = t->size;
581 goto done;
582 case BTF_KIND_PTR:
583 size = btf_ptr_sz(btf);
584 goto done;
585 case BTF_KIND_TYPEDEF:
586 case BTF_KIND_VOLATILE:
587 case BTF_KIND_CONST:
588 case BTF_KIND_RESTRICT:
589 case BTF_KIND_VAR:
590 type_id = t->type;
591 break;
592 case BTF_KIND_ARRAY:
593 array = btf_array(t);
594 if (nelems && array->nelems > UINT32_MAX / nelems)
595 return -E2BIG;
596 nelems *= array->nelems;
597 type_id = array->type;
598 break;
599 default:
600 return -EINVAL;
601 }
602
603 t = btf__type_by_id(btf, type_id);
604 }
605
606 done:
607 if (size < 0)
608 return -EINVAL;
609 if (nelems && size > UINT32_MAX / nelems)
610 return -E2BIG;
611
612 return nelems * size;
613 }
614
btf__align_of(const struct btf * btf,__u32 id)615 int btf__align_of(const struct btf *btf, __u32 id)
616 {
617 const struct btf_type *t = btf__type_by_id(btf, id);
618 __u16 kind = btf_kind(t);
619
620 switch (kind) {
621 case BTF_KIND_INT:
622 case BTF_KIND_ENUM:
623 case BTF_KIND_FLOAT:
624 return min(btf_ptr_sz(btf), (size_t)t->size);
625 case BTF_KIND_PTR:
626 return btf_ptr_sz(btf);
627 case BTF_KIND_TYPEDEF:
628 case BTF_KIND_VOLATILE:
629 case BTF_KIND_CONST:
630 case BTF_KIND_RESTRICT:
631 return btf__align_of(btf, t->type);
632 case BTF_KIND_ARRAY:
633 return btf__align_of(btf, btf_array(t)->type);
634 case BTF_KIND_STRUCT:
635 case BTF_KIND_UNION: {
636 const struct btf_member *m = btf_members(t);
637 __u16 vlen = btf_vlen(t);
638 int i, max_align = 1, align;
639
640 for (i = 0; i < vlen; i++, m++) {
641 align = btf__align_of(btf, m->type);
642 if (align <= 0)
643 return align;
644 max_align = max(max_align, align);
645 }
646
647 return max_align;
648 }
649 default:
650 pr_warn("unsupported BTF_KIND:%u\n", btf_kind(t));
651 return 0;
652 }
653 }
654
btf__resolve_type(const struct btf * btf,__u32 type_id)655 int btf__resolve_type(const struct btf *btf, __u32 type_id)
656 {
657 const struct btf_type *t;
658 int depth = 0;
659
660 t = btf__type_by_id(btf, type_id);
661 while (depth < MAX_RESOLVE_DEPTH &&
662 !btf_type_is_void_or_null(t) &&
663 (btf_is_mod(t) || btf_is_typedef(t) || btf_is_var(t))) {
664 type_id = t->type;
665 t = btf__type_by_id(btf, type_id);
666 depth++;
667 }
668
669 if (depth == MAX_RESOLVE_DEPTH || btf_type_is_void_or_null(t))
670 return -EINVAL;
671
672 return type_id;
673 }
674
btf__find_by_name(const struct btf * btf,const char * type_name)675 __s32 btf__find_by_name(const struct btf *btf, const char *type_name)
676 {
677 __u32 i, nr_types = btf__get_nr_types(btf);
678
679 if (!strcmp(type_name, "void"))
680 return 0;
681
682 for (i = 1; i <= nr_types; i++) {
683 const struct btf_type *t = btf__type_by_id(btf, i);
684 const char *name = btf__name_by_offset(btf, t->name_off);
685
686 if (name && !strcmp(type_name, name))
687 return i;
688 }
689
690 return -ENOENT;
691 }
692
btf__find_by_name_kind(const struct btf * btf,const char * type_name,__u32 kind)693 __s32 btf__find_by_name_kind(const struct btf *btf, const char *type_name,
694 __u32 kind)
695 {
696 __u32 i, nr_types = btf__get_nr_types(btf);
697
698 if (kind == BTF_KIND_UNKN || !strcmp(type_name, "void"))
699 return 0;
700
701 for (i = 1; i <= nr_types; i++) {
702 const struct btf_type *t = btf__type_by_id(btf, i);
703 const char *name;
704
705 if (btf_kind(t) != kind)
706 continue;
707 name = btf__name_by_offset(btf, t->name_off);
708 if (name && !strcmp(type_name, name))
709 return i;
710 }
711
712 return -ENOENT;
713 }
714
btf_is_modifiable(const struct btf * btf)715 static bool btf_is_modifiable(const struct btf *btf)
716 {
717 return (void *)btf->hdr != btf->raw_data;
718 }
719
btf__free(struct btf * btf)720 void btf__free(struct btf *btf)
721 {
722 if (IS_ERR_OR_NULL(btf))
723 return;
724
725 if (btf->fd >= 0)
726 close(btf->fd);
727
728 if (btf_is_modifiable(btf)) {
729 /* if BTF was modified after loading, it will have a split
730 * in-memory representation for header, types, and strings
731 * sections, so we need to free all of them individually. It
732 * might still have a cached contiguous raw data present,
733 * which will be unconditionally freed below.
734 */
735 free(btf->hdr);
736 free(btf->types_data);
737 strset__free(btf->strs_set);
738 }
739 free(btf->raw_data);
740 free(btf->raw_data_swapped);
741 free(btf->type_offs);
742 free(btf);
743 }
744
btf_new_empty(struct btf * base_btf)745 static struct btf *btf_new_empty(struct btf *base_btf)
746 {
747 struct btf *btf;
748
749 btf = calloc(1, sizeof(*btf));
750 if (!btf)
751 return ERR_PTR(-ENOMEM);
752
753 btf->nr_types = 0;
754 btf->start_id = 1;
755 btf->start_str_off = 0;
756 btf->fd = -1;
757 btf->ptr_sz = sizeof(void *);
758 btf->swapped_endian = false;
759
760 if (base_btf) {
761 btf->base_btf = base_btf;
762 btf->start_id = btf__get_nr_types(base_btf) + 1;
763 btf->start_str_off = base_btf->hdr->str_len;
764 }
765
766 /* +1 for empty string at offset 0 */
767 btf->raw_size = sizeof(struct btf_header) + (base_btf ? 0 : 1);
768 btf->raw_data = calloc(1, btf->raw_size);
769 if (!btf->raw_data) {
770 free(btf);
771 return ERR_PTR(-ENOMEM);
772 }
773
774 btf->hdr = btf->raw_data;
775 btf->hdr->hdr_len = sizeof(struct btf_header);
776 btf->hdr->magic = BTF_MAGIC;
777 btf->hdr->version = BTF_VERSION;
778
779 btf->types_data = btf->raw_data + btf->hdr->hdr_len;
780 btf->strs_data = btf->raw_data + btf->hdr->hdr_len;
781 btf->hdr->str_len = base_btf ? 0 : 1; /* empty string at offset 0 */
782
783 return btf;
784 }
785
btf__new_empty(void)786 struct btf *btf__new_empty(void)
787 {
788 return btf_new_empty(NULL);
789 }
790
btf__new_empty_split(struct btf * base_btf)791 struct btf *btf__new_empty_split(struct btf *base_btf)
792 {
793 return btf_new_empty(base_btf);
794 }
795
btf_new(const void * data,__u32 size,struct btf * base_btf)796 static struct btf *btf_new(const void *data, __u32 size, struct btf *base_btf)
797 {
798 struct btf *btf;
799 int err;
800
801 btf = calloc(1, sizeof(struct btf));
802 if (!btf)
803 return ERR_PTR(-ENOMEM);
804
805 btf->nr_types = 0;
806 btf->start_id = 1;
807 btf->start_str_off = 0;
808
809 if (base_btf) {
810 btf->base_btf = base_btf;
811 btf->start_id = btf__get_nr_types(base_btf) + 1;
812 btf->start_str_off = base_btf->hdr->str_len;
813 }
814
815 btf->raw_data = malloc(size);
816 if (!btf->raw_data) {
817 err = -ENOMEM;
818 goto done;
819 }
820 memcpy(btf->raw_data, data, size);
821 btf->raw_size = size;
822
823 btf->hdr = btf->raw_data;
824 err = btf_parse_hdr(btf);
825 if (err)
826 goto done;
827
828 btf->strs_data = btf->raw_data + btf->hdr->hdr_len + btf->hdr->str_off;
829 btf->types_data = btf->raw_data + btf->hdr->hdr_len + btf->hdr->type_off;
830
831 err = btf_parse_str_sec(btf);
832 err = err ?: btf_parse_type_sec(btf);
833 if (err)
834 goto done;
835
836 btf->fd = -1;
837
838 done:
839 if (err) {
840 btf__free(btf);
841 return ERR_PTR(err);
842 }
843
844 return btf;
845 }
846
btf__new(const void * data,__u32 size)847 struct btf *btf__new(const void *data, __u32 size)
848 {
849 return btf_new(data, size, NULL);
850 }
851
btf_parse_elf(const char * path,struct btf * base_btf,struct btf_ext ** btf_ext)852 static struct btf *btf_parse_elf(const char *path, struct btf *base_btf,
853 struct btf_ext **btf_ext)
854 {
855 Elf_Data *btf_data = NULL, *btf_ext_data = NULL;
856 int err = 0, fd = -1, idx = 0;
857 struct btf *btf = NULL;
858 Elf_Scn *scn = NULL;
859 Elf *elf = NULL;
860 GElf_Ehdr ehdr;
861 size_t shstrndx;
862
863 if (elf_version(EV_CURRENT) == EV_NONE) {
864 pr_warn("failed to init libelf for %s\n", path);
865 return ERR_PTR(-LIBBPF_ERRNO__LIBELF);
866 }
867
868 fd = open(path, O_RDONLY);
869 if (fd < 0) {
870 err = -errno;
871 pr_warn("failed to open %s: %s\n", path, strerror(errno));
872 return ERR_PTR(err);
873 }
874
875 err = -LIBBPF_ERRNO__FORMAT;
876
877 elf = elf_begin(fd, ELF_C_READ, NULL);
878 if (!elf) {
879 pr_warn("failed to open %s as ELF file\n", path);
880 goto done;
881 }
882 if (!gelf_getehdr(elf, &ehdr)) {
883 pr_warn("failed to get EHDR from %s\n", path);
884 goto done;
885 }
886
887 if (elf_getshdrstrndx(elf, &shstrndx)) {
888 pr_warn("failed to get section names section index for %s\n",
889 path);
890 goto done;
891 }
892
893 if (!elf_rawdata(elf_getscn(elf, shstrndx), NULL)) {
894 pr_warn("failed to get e_shstrndx from %s\n", path);
895 goto done;
896 }
897
898 while ((scn = elf_nextscn(elf, scn)) != NULL) {
899 GElf_Shdr sh;
900 char *name;
901
902 idx++;
903 if (gelf_getshdr(scn, &sh) != &sh) {
904 pr_warn("failed to get section(%d) header from %s\n",
905 idx, path);
906 goto done;
907 }
908 name = elf_strptr(elf, shstrndx, sh.sh_name);
909 if (!name) {
910 pr_warn("failed to get section(%d) name from %s\n",
911 idx, path);
912 goto done;
913 }
914 if (strcmp(name, BTF_ELF_SEC) == 0) {
915 btf_data = elf_getdata(scn, 0);
916 if (!btf_data) {
917 pr_warn("failed to get section(%d, %s) data from %s\n",
918 idx, name, path);
919 goto done;
920 }
921 continue;
922 } else if (btf_ext && strcmp(name, BTF_EXT_ELF_SEC) == 0) {
923 btf_ext_data = elf_getdata(scn, 0);
924 if (!btf_ext_data) {
925 pr_warn("failed to get section(%d, %s) data from %s\n",
926 idx, name, path);
927 goto done;
928 }
929 continue;
930 }
931 }
932
933 err = 0;
934
935 if (!btf_data) {
936 err = -ENOENT;
937 goto done;
938 }
939 btf = btf_new(btf_data->d_buf, btf_data->d_size, base_btf);
940 if (IS_ERR(btf))
941 goto done;
942
943 switch (gelf_getclass(elf)) {
944 case ELFCLASS32:
945 btf__set_pointer_size(btf, 4);
946 break;
947 case ELFCLASS64:
948 btf__set_pointer_size(btf, 8);
949 break;
950 default:
951 pr_warn("failed to get ELF class (bitness) for %s\n", path);
952 break;
953 }
954
955 if (btf_ext && btf_ext_data) {
956 *btf_ext = btf_ext__new(btf_ext_data->d_buf,
957 btf_ext_data->d_size);
958 if (IS_ERR(*btf_ext))
959 goto done;
960 } else if (btf_ext) {
961 *btf_ext = NULL;
962 }
963 done:
964 if (elf)
965 elf_end(elf);
966 close(fd);
967
968 if (err)
969 return ERR_PTR(err);
970 /*
971 * btf is always parsed before btf_ext, so no need to clean up
972 * btf_ext, if btf loading failed
973 */
974 if (IS_ERR(btf))
975 return btf;
976 if (btf_ext && IS_ERR(*btf_ext)) {
977 btf__free(btf);
978 err = PTR_ERR(*btf_ext);
979 return ERR_PTR(err);
980 }
981 return btf;
982 }
983
btf__parse_elf(const char * path,struct btf_ext ** btf_ext)984 struct btf *btf__parse_elf(const char *path, struct btf_ext **btf_ext)
985 {
986 return btf_parse_elf(path, NULL, btf_ext);
987 }
988
btf__parse_elf_split(const char * path,struct btf * base_btf)989 struct btf *btf__parse_elf_split(const char *path, struct btf *base_btf)
990 {
991 return btf_parse_elf(path, base_btf, NULL);
992 }
993
btf_parse_raw(const char * path,struct btf * base_btf)994 static struct btf *btf_parse_raw(const char *path, struct btf *base_btf)
995 {
996 struct btf *btf = NULL;
997 void *data = NULL;
998 FILE *f = NULL;
999 __u16 magic;
1000 int err = 0;
1001 long sz;
1002
1003 f = fopen(path, "rb");
1004 if (!f) {
1005 err = -errno;
1006 goto err_out;
1007 }
1008
1009 /* check BTF magic */
1010 if (fread(&magic, 1, sizeof(magic), f) < sizeof(magic)) {
1011 err = -EIO;
1012 goto err_out;
1013 }
1014 if (magic != BTF_MAGIC && magic != bswap_16(BTF_MAGIC)) {
1015 /* definitely not a raw BTF */
1016 err = -EPROTO;
1017 goto err_out;
1018 }
1019
1020 /* get file size */
1021 if (fseek(f, 0, SEEK_END)) {
1022 err = -errno;
1023 goto err_out;
1024 }
1025 sz = ftell(f);
1026 if (sz < 0) {
1027 err = -errno;
1028 goto err_out;
1029 }
1030 /* rewind to the start */
1031 if (fseek(f, 0, SEEK_SET)) {
1032 err = -errno;
1033 goto err_out;
1034 }
1035
1036 /* pre-alloc memory and read all of BTF data */
1037 data = malloc(sz);
1038 if (!data) {
1039 err = -ENOMEM;
1040 goto err_out;
1041 }
1042 if (fread(data, 1, sz, f) < sz) {
1043 err = -EIO;
1044 goto err_out;
1045 }
1046
1047 /* finally parse BTF data */
1048 btf = btf_new(data, sz, base_btf);
1049
1050 err_out:
1051 free(data);
1052 if (f)
1053 fclose(f);
1054 return err ? ERR_PTR(err) : btf;
1055 }
1056
btf__parse_raw(const char * path)1057 struct btf *btf__parse_raw(const char *path)
1058 {
1059 return btf_parse_raw(path, NULL);
1060 }
1061
btf__parse_raw_split(const char * path,struct btf * base_btf)1062 struct btf *btf__parse_raw_split(const char *path, struct btf *base_btf)
1063 {
1064 return btf_parse_raw(path, base_btf);
1065 }
1066
btf_parse(const char * path,struct btf * base_btf,struct btf_ext ** btf_ext)1067 static struct btf *btf_parse(const char *path, struct btf *base_btf, struct btf_ext **btf_ext)
1068 {
1069 struct btf *btf;
1070
1071 if (btf_ext)
1072 *btf_ext = NULL;
1073
1074 btf = btf_parse_raw(path, base_btf);
1075 if (!IS_ERR(btf) || PTR_ERR(btf) != -EPROTO)
1076 return btf;
1077
1078 return btf_parse_elf(path, base_btf, btf_ext);
1079 }
1080
btf__parse(const char * path,struct btf_ext ** btf_ext)1081 struct btf *btf__parse(const char *path, struct btf_ext **btf_ext)
1082 {
1083 return btf_parse(path, NULL, btf_ext);
1084 }
1085
btf__parse_split(const char * path,struct btf * base_btf)1086 struct btf *btf__parse_split(const char *path, struct btf *base_btf)
1087 {
1088 return btf_parse(path, base_btf, NULL);
1089 }
1090
compare_vsi_off(const void * _a,const void * _b)1091 static int compare_vsi_off(const void *_a, const void *_b)
1092 {
1093 const struct btf_var_secinfo *a = _a;
1094 const struct btf_var_secinfo *b = _b;
1095
1096 return a->offset - b->offset;
1097 }
1098
btf_fixup_datasec(struct bpf_object * obj,struct btf * btf,struct btf_type * t)1099 static int btf_fixup_datasec(struct bpf_object *obj, struct btf *btf,
1100 struct btf_type *t)
1101 {
1102 __u32 size = 0, off = 0, i, vars = btf_vlen(t);
1103 const char *name = btf__name_by_offset(btf, t->name_off);
1104 const struct btf_type *t_var;
1105 struct btf_var_secinfo *vsi;
1106 const struct btf_var *var;
1107 int ret;
1108
1109 if (!name) {
1110 pr_debug("No name found in string section for DATASEC kind.\n");
1111 return -ENOENT;
1112 }
1113
1114 /* .extern datasec size and var offsets were set correctly during
1115 * extern collection step, so just skip straight to sorting variables
1116 */
1117 if (t->size)
1118 goto sort_vars;
1119
1120 ret = bpf_object__section_size(obj, name, &size);
1121 if (ret || !size || (t->size && t->size != size)) {
1122 pr_debug("Invalid size for section %s: %u bytes\n", name, size);
1123 return -ENOENT;
1124 }
1125
1126 t->size = size;
1127
1128 for (i = 0, vsi = btf_var_secinfos(t); i < vars; i++, vsi++) {
1129 t_var = btf__type_by_id(btf, vsi->type);
1130 var = btf_var(t_var);
1131
1132 if (!btf_is_var(t_var)) {
1133 pr_debug("Non-VAR type seen in section %s\n", name);
1134 return -EINVAL;
1135 }
1136
1137 if (var->linkage == BTF_VAR_STATIC)
1138 continue;
1139
1140 name = btf__name_by_offset(btf, t_var->name_off);
1141 if (!name) {
1142 pr_debug("No name found in string section for VAR kind\n");
1143 return -ENOENT;
1144 }
1145
1146 ret = bpf_object__variable_offset(obj, name, &off);
1147 if (ret) {
1148 pr_debug("No offset found in symbol table for VAR %s\n",
1149 name);
1150 return -ENOENT;
1151 }
1152
1153 vsi->offset = off;
1154 }
1155
1156 sort_vars:
1157 qsort(btf_var_secinfos(t), vars, sizeof(*vsi), compare_vsi_off);
1158 return 0;
1159 }
1160
btf__finalize_data(struct bpf_object * obj,struct btf * btf)1161 int btf__finalize_data(struct bpf_object *obj, struct btf *btf)
1162 {
1163 int err = 0;
1164 __u32 i;
1165
1166 for (i = 1; i <= btf->nr_types; i++) {
1167 struct btf_type *t = btf_type_by_id(btf, i);
1168
1169 /* Loader needs to fix up some of the things compiler
1170 * couldn't get its hands on while emitting BTF. This
1171 * is section size and global variable offset. We use
1172 * the info from the ELF itself for this purpose.
1173 */
1174 if (btf_is_datasec(t)) {
1175 err = btf_fixup_datasec(obj, btf, t);
1176 if (err)
1177 break;
1178 }
1179 }
1180
1181 return err;
1182 }
1183
1184 static void *btf_get_raw_data(const struct btf *btf, __u32 *size, bool swap_endian);
1185
btf__load(struct btf * btf)1186 int btf__load(struct btf *btf)
1187 {
1188 __u32 log_buf_size = 0, raw_size;
1189 char *log_buf = NULL;
1190 void *raw_data;
1191 int err = 0;
1192
1193 if (btf->fd >= 0)
1194 return -EEXIST;
1195
1196 retry_load:
1197 if (log_buf_size) {
1198 log_buf = malloc(log_buf_size);
1199 if (!log_buf)
1200 return -ENOMEM;
1201
1202 *log_buf = 0;
1203 }
1204
1205 raw_data = btf_get_raw_data(btf, &raw_size, false);
1206 if (!raw_data) {
1207 err = -ENOMEM;
1208 goto done;
1209 }
1210 /* cache native raw data representation */
1211 btf->raw_size = raw_size;
1212 btf->raw_data = raw_data;
1213
1214 btf->fd = bpf_load_btf(raw_data, raw_size, log_buf, log_buf_size, false);
1215 if (btf->fd < 0) {
1216 if (!log_buf || errno == ENOSPC) {
1217 log_buf_size = max((__u32)BPF_LOG_BUF_SIZE,
1218 log_buf_size << 1);
1219 free(log_buf);
1220 goto retry_load;
1221 }
1222
1223 err = -errno;
1224 pr_warn("Error loading BTF: %s(%d)\n", strerror(errno), errno);
1225 if (*log_buf)
1226 pr_warn("%s\n", log_buf);
1227 goto done;
1228 }
1229
1230 done:
1231 free(log_buf);
1232 return err;
1233 }
1234
btf__fd(const struct btf * btf)1235 int btf__fd(const struct btf *btf)
1236 {
1237 return btf->fd;
1238 }
1239
btf__set_fd(struct btf * btf,int fd)1240 void btf__set_fd(struct btf *btf, int fd)
1241 {
1242 btf->fd = fd;
1243 }
1244
btf_strs_data(const struct btf * btf)1245 static const void *btf_strs_data(const struct btf *btf)
1246 {
1247 return btf->strs_data ? btf->strs_data : strset__data(btf->strs_set);
1248 }
1249
btf_get_raw_data(const struct btf * btf,__u32 * size,bool swap_endian)1250 static void *btf_get_raw_data(const struct btf *btf, __u32 *size, bool swap_endian)
1251 {
1252 struct btf_header *hdr = btf->hdr;
1253 struct btf_type *t;
1254 void *data, *p;
1255 __u32 data_sz;
1256 int i;
1257
1258 data = swap_endian ? btf->raw_data_swapped : btf->raw_data;
1259 if (data) {
1260 *size = btf->raw_size;
1261 return data;
1262 }
1263
1264 data_sz = hdr->hdr_len + hdr->type_len + hdr->str_len;
1265 data = calloc(1, data_sz);
1266 if (!data)
1267 return NULL;
1268 p = data;
1269
1270 memcpy(p, hdr, hdr->hdr_len);
1271 if (swap_endian)
1272 btf_bswap_hdr(p);
1273 p += hdr->hdr_len;
1274
1275 memcpy(p, btf->types_data, hdr->type_len);
1276 if (swap_endian) {
1277 for (i = 0; i < btf->nr_types; i++) {
1278 t = p + btf->type_offs[i];
1279 /* btf_bswap_type_rest() relies on native t->info, so
1280 * we swap base type info after we swapped all the
1281 * additional information
1282 */
1283 if (btf_bswap_type_rest(t))
1284 goto err_out;
1285 btf_bswap_type_base(t);
1286 }
1287 }
1288 p += hdr->type_len;
1289
1290 memcpy(p, btf_strs_data(btf), hdr->str_len);
1291 p += hdr->str_len;
1292
1293 *size = data_sz;
1294 return data;
1295 err_out:
1296 free(data);
1297 return NULL;
1298 }
1299
btf__get_raw_data(const struct btf * btf_ro,__u32 * size)1300 const void *btf__get_raw_data(const struct btf *btf_ro, __u32 *size)
1301 {
1302 struct btf *btf = (struct btf *)btf_ro;
1303 __u32 data_sz;
1304 void *data;
1305
1306 data = btf_get_raw_data(btf, &data_sz, btf->swapped_endian);
1307 if (!data)
1308 return NULL;
1309
1310 btf->raw_size = data_sz;
1311 if (btf->swapped_endian)
1312 btf->raw_data_swapped = data;
1313 else
1314 btf->raw_data = data;
1315 *size = data_sz;
1316 return data;
1317 }
1318
btf__str_by_offset(const struct btf * btf,__u32 offset)1319 const char *btf__str_by_offset(const struct btf *btf, __u32 offset)
1320 {
1321 if (offset < btf->start_str_off)
1322 return btf__str_by_offset(btf->base_btf, offset);
1323 else if (offset - btf->start_str_off < btf->hdr->str_len)
1324 return btf_strs_data(btf) + (offset - btf->start_str_off);
1325 else
1326 return NULL;
1327 }
1328
btf__name_by_offset(const struct btf * btf,__u32 offset)1329 const char *btf__name_by_offset(const struct btf *btf, __u32 offset)
1330 {
1331 return btf__str_by_offset(btf, offset);
1332 }
1333
btf_get_from_fd(int btf_fd,struct btf * base_btf)1334 struct btf *btf_get_from_fd(int btf_fd, struct btf *base_btf)
1335 {
1336 struct bpf_btf_info btf_info;
1337 __u32 len = sizeof(btf_info);
1338 __u32 last_size;
1339 struct btf *btf;
1340 void *ptr;
1341 int err;
1342
1343 /* we won't know btf_size until we call bpf_obj_get_info_by_fd(). so
1344 * let's start with a sane default - 4KiB here - and resize it only if
1345 * bpf_obj_get_info_by_fd() needs a bigger buffer.
1346 */
1347 last_size = 4096;
1348 ptr = malloc(last_size);
1349 if (!ptr)
1350 return ERR_PTR(-ENOMEM);
1351
1352 memset(&btf_info, 0, sizeof(btf_info));
1353 btf_info.btf = ptr_to_u64(ptr);
1354 btf_info.btf_size = last_size;
1355 err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len);
1356
1357 if (!err && btf_info.btf_size > last_size) {
1358 void *temp_ptr;
1359
1360 last_size = btf_info.btf_size;
1361 temp_ptr = realloc(ptr, last_size);
1362 if (!temp_ptr) {
1363 btf = ERR_PTR(-ENOMEM);
1364 goto exit_free;
1365 }
1366 ptr = temp_ptr;
1367
1368 len = sizeof(btf_info);
1369 memset(&btf_info, 0, sizeof(btf_info));
1370 btf_info.btf = ptr_to_u64(ptr);
1371 btf_info.btf_size = last_size;
1372
1373 err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len);
1374 }
1375
1376 if (err || btf_info.btf_size > last_size) {
1377 btf = err ? ERR_PTR(-errno) : ERR_PTR(-E2BIG);
1378 goto exit_free;
1379 }
1380
1381 btf = btf_new(ptr, btf_info.btf_size, base_btf);
1382
1383 exit_free:
1384 free(ptr);
1385 return btf;
1386 }
1387
btf__get_from_id(__u32 id,struct btf ** btf)1388 int btf__get_from_id(__u32 id, struct btf **btf)
1389 {
1390 struct btf *res;
1391 int btf_fd;
1392
1393 *btf = NULL;
1394 btf_fd = bpf_btf_get_fd_by_id(id);
1395 if (btf_fd < 0)
1396 return -errno;
1397
1398 res = btf_get_from_fd(btf_fd, NULL);
1399 close(btf_fd);
1400 if (IS_ERR(res))
1401 return PTR_ERR(res);
1402
1403 *btf = res;
1404 return 0;
1405 }
1406
btf__get_map_kv_tids(const struct btf * btf,const char * map_name,__u32 expected_key_size,__u32 expected_value_size,__u32 * key_type_id,__u32 * value_type_id)1407 int btf__get_map_kv_tids(const struct btf *btf, const char *map_name,
1408 __u32 expected_key_size, __u32 expected_value_size,
1409 __u32 *key_type_id, __u32 *value_type_id)
1410 {
1411 const struct btf_type *container_type;
1412 const struct btf_member *key, *value;
1413 const size_t max_name = 256;
1414 char container_name[max_name];
1415 __s64 key_size, value_size;
1416 __s32 container_id;
1417
1418 if (snprintf(container_name, max_name, "____btf_map_%s", map_name) ==
1419 max_name) {
1420 pr_warn("map:%s length of '____btf_map_%s' is too long\n",
1421 map_name, map_name);
1422 return -EINVAL;
1423 }
1424
1425 container_id = btf__find_by_name(btf, container_name);
1426 if (container_id < 0) {
1427 pr_debug("map:%s container_name:%s cannot be found in BTF. Missing BPF_ANNOTATE_KV_PAIR?\n",
1428 map_name, container_name);
1429 return container_id;
1430 }
1431
1432 container_type = btf__type_by_id(btf, container_id);
1433 if (!container_type) {
1434 pr_warn("map:%s cannot find BTF type for container_id:%u\n",
1435 map_name, container_id);
1436 return -EINVAL;
1437 }
1438
1439 if (!btf_is_struct(container_type) || btf_vlen(container_type) < 2) {
1440 pr_warn("map:%s container_name:%s is an invalid container struct\n",
1441 map_name, container_name);
1442 return -EINVAL;
1443 }
1444
1445 key = btf_members(container_type);
1446 value = key + 1;
1447
1448 key_size = btf__resolve_size(btf, key->type);
1449 if (key_size < 0) {
1450 pr_warn("map:%s invalid BTF key_type_size\n", map_name);
1451 return key_size;
1452 }
1453
1454 if (expected_key_size != key_size) {
1455 pr_warn("map:%s btf_key_type_size:%u != map_def_key_size:%u\n",
1456 map_name, (__u32)key_size, expected_key_size);
1457 return -EINVAL;
1458 }
1459
1460 value_size = btf__resolve_size(btf, value->type);
1461 if (value_size < 0) {
1462 pr_warn("map:%s invalid BTF value_type_size\n", map_name);
1463 return value_size;
1464 }
1465
1466 if (expected_value_size != value_size) {
1467 pr_warn("map:%s btf_value_type_size:%u != map_def_value_size:%u\n",
1468 map_name, (__u32)value_size, expected_value_size);
1469 return -EINVAL;
1470 }
1471
1472 *key_type_id = key->type;
1473 *value_type_id = value->type;
1474
1475 return 0;
1476 }
1477
btf_invalidate_raw_data(struct btf * btf)1478 static void btf_invalidate_raw_data(struct btf *btf)
1479 {
1480 if (btf->raw_data) {
1481 free(btf->raw_data);
1482 btf->raw_data = NULL;
1483 }
1484 if (btf->raw_data_swapped) {
1485 free(btf->raw_data_swapped);
1486 btf->raw_data_swapped = NULL;
1487 }
1488 }
1489
1490 /* Ensure BTF is ready to be modified (by splitting into a three memory
1491 * regions for header, types, and strings). Also invalidate cached
1492 * raw_data, if any.
1493 */
btf_ensure_modifiable(struct btf * btf)1494 static int btf_ensure_modifiable(struct btf *btf)
1495 {
1496 void *hdr, *types;
1497 struct strset *set = NULL;
1498 int err = -ENOMEM;
1499
1500 if (btf_is_modifiable(btf)) {
1501 /* any BTF modification invalidates raw_data */
1502 btf_invalidate_raw_data(btf);
1503 return 0;
1504 }
1505
1506 /* split raw data into three memory regions */
1507 hdr = malloc(btf->hdr->hdr_len);
1508 types = malloc(btf->hdr->type_len);
1509 if (!hdr || !types)
1510 goto err_out;
1511
1512 memcpy(hdr, btf->hdr, btf->hdr->hdr_len);
1513 memcpy(types, btf->types_data, btf->hdr->type_len);
1514
1515 /* build lookup index for all strings */
1516 set = strset__new(BTF_MAX_STR_OFFSET, btf->strs_data, btf->hdr->str_len);
1517 if (IS_ERR(set)) {
1518 err = PTR_ERR(set);
1519 goto err_out;
1520 }
1521
1522 /* only when everything was successful, update internal state */
1523 btf->hdr = hdr;
1524 btf->types_data = types;
1525 btf->types_data_cap = btf->hdr->type_len;
1526 btf->strs_data = NULL;
1527 btf->strs_set = set;
1528 /* if BTF was created from scratch, all strings are guaranteed to be
1529 * unique and deduplicated
1530 */
1531 if (btf->hdr->str_len == 0)
1532 btf->strs_deduped = true;
1533 if (!btf->base_btf && btf->hdr->str_len == 1)
1534 btf->strs_deduped = true;
1535
1536 /* invalidate raw_data representation */
1537 btf_invalidate_raw_data(btf);
1538
1539 return 0;
1540
1541 err_out:
1542 strset__free(set);
1543 free(hdr);
1544 free(types);
1545 return err;
1546 }
1547
1548 /* Find an offset in BTF string section that corresponds to a given string *s*.
1549 * Returns:
1550 * - >0 offset into string section, if string is found;
1551 * - -ENOENT, if string is not in the string section;
1552 * - <0, on any other error.
1553 */
btf__find_str(struct btf * btf,const char * s)1554 int btf__find_str(struct btf *btf, const char *s)
1555 {
1556 int off;
1557
1558 if (btf->base_btf) {
1559 off = btf__find_str(btf->base_btf, s);
1560 if (off != -ENOENT)
1561 return off;
1562 }
1563
1564 /* BTF needs to be in a modifiable state to build string lookup index */
1565 if (btf_ensure_modifiable(btf))
1566 return -ENOMEM;
1567
1568 off = strset__find_str(btf->strs_set, s);
1569 if (off < 0)
1570 return off;
1571
1572 return btf->start_str_off + off;
1573 }
1574
1575 /* Add a string s to the BTF string section.
1576 * Returns:
1577 * - > 0 offset into string section, on success;
1578 * - < 0, on error.
1579 */
btf__add_str(struct btf * btf,const char * s)1580 int btf__add_str(struct btf *btf, const char *s)
1581 {
1582 int off;
1583
1584 if (btf->base_btf) {
1585 off = btf__find_str(btf->base_btf, s);
1586 if (off != -ENOENT)
1587 return off;
1588 }
1589
1590 if (btf_ensure_modifiable(btf))
1591 return -ENOMEM;
1592
1593 off = strset__add_str(btf->strs_set, s);
1594 if (off < 0)
1595 return off;
1596
1597 btf->hdr->str_len = strset__data_size(btf->strs_set);
1598
1599 return btf->start_str_off + off;
1600 }
1601
btf_add_type_mem(struct btf * btf,size_t add_sz)1602 static void *btf_add_type_mem(struct btf *btf, size_t add_sz)
1603 {
1604 return libbpf_add_mem(&btf->types_data, &btf->types_data_cap, 1,
1605 btf->hdr->type_len, UINT_MAX, add_sz);
1606 }
1607
btf_type_inc_vlen(struct btf_type * t)1608 static void btf_type_inc_vlen(struct btf_type *t)
1609 {
1610 t->info = btf_type_info(btf_kind(t), btf_vlen(t) + 1, btf_kflag(t));
1611 }
1612
btf_commit_type(struct btf * btf,int data_sz)1613 static int btf_commit_type(struct btf *btf, int data_sz)
1614 {
1615 int err;
1616
1617 err = btf_add_type_idx_entry(btf, btf->hdr->type_len);
1618 if (err)
1619 return err;
1620
1621 btf->hdr->type_len += data_sz;
1622 btf->hdr->str_off += data_sz;
1623 btf->nr_types++;
1624 return btf->start_id + btf->nr_types - 1;
1625 }
1626
1627 struct btf_pipe {
1628 const struct btf *src;
1629 struct btf *dst;
1630 };
1631
btf_rewrite_str(__u32 * str_off,void * ctx)1632 static int btf_rewrite_str(__u32 *str_off, void *ctx)
1633 {
1634 struct btf_pipe *p = ctx;
1635 int off;
1636
1637 if (!*str_off) /* nothing to do for empty strings */
1638 return 0;
1639
1640 off = btf__add_str(p->dst, btf__str_by_offset(p->src, *str_off));
1641 if (off < 0)
1642 return off;
1643
1644 *str_off = off;
1645 return 0;
1646 }
1647
btf__add_type(struct btf * btf,const struct btf * src_btf,const struct btf_type * src_type)1648 int btf__add_type(struct btf *btf, const struct btf *src_btf, const struct btf_type *src_type)
1649 {
1650 struct btf_pipe p = { .src = src_btf, .dst = btf };
1651 struct btf_type *t;
1652 int sz, err;
1653
1654 sz = btf_type_size(src_type);
1655 if (sz < 0)
1656 return sz;
1657
1658 /* deconstruct BTF, if necessary, and invalidate raw_data */
1659 if (btf_ensure_modifiable(btf))
1660 return -ENOMEM;
1661
1662 t = btf_add_type_mem(btf, sz);
1663 if (!t)
1664 return -ENOMEM;
1665
1666 memcpy(t, src_type, sz);
1667
1668 err = btf_type_visit_str_offs(t, btf_rewrite_str, &p);
1669 if (err)
1670 return err;
1671
1672 return btf_commit_type(btf, sz);
1673 }
1674
1675 /*
1676 * Append new BTF_KIND_INT type with:
1677 * - *name* - non-empty, non-NULL type name;
1678 * - *sz* - power-of-2 (1, 2, 4, ..) size of the type, in bytes;
1679 * - encoding is a combination of BTF_INT_SIGNED, BTF_INT_CHAR, BTF_INT_BOOL.
1680 * Returns:
1681 * - >0, type ID of newly added BTF type;
1682 * - <0, on error.
1683 */
btf__add_int(struct btf * btf,const char * name,size_t byte_sz,int encoding)1684 int btf__add_int(struct btf *btf, const char *name, size_t byte_sz, int encoding)
1685 {
1686 struct btf_type *t;
1687 int sz, name_off;
1688
1689 /* non-empty name */
1690 if (!name || !name[0])
1691 return -EINVAL;
1692 /* byte_sz must be power of 2 */
1693 if (!byte_sz || (byte_sz & (byte_sz - 1)) || byte_sz > 16)
1694 return -EINVAL;
1695 if (encoding & ~(BTF_INT_SIGNED | BTF_INT_CHAR | BTF_INT_BOOL))
1696 return -EINVAL;
1697
1698 /* deconstruct BTF, if necessary, and invalidate raw_data */
1699 if (btf_ensure_modifiable(btf))
1700 return -ENOMEM;
1701
1702 sz = sizeof(struct btf_type) + sizeof(int);
1703 t = btf_add_type_mem(btf, sz);
1704 if (!t)
1705 return -ENOMEM;
1706
1707 /* if something goes wrong later, we might end up with an extra string,
1708 * but that shouldn't be a problem, because BTF can't be constructed
1709 * completely anyway and will most probably be just discarded
1710 */
1711 name_off = btf__add_str(btf, name);
1712 if (name_off < 0)
1713 return name_off;
1714
1715 t->name_off = name_off;
1716 t->info = btf_type_info(BTF_KIND_INT, 0, 0);
1717 t->size = byte_sz;
1718 /* set INT info, we don't allow setting legacy bit offset/size */
1719 *(__u32 *)(t + 1) = (encoding << 24) | (byte_sz * 8);
1720
1721 return btf_commit_type(btf, sz);
1722 }
1723
1724 /*
1725 * Append new BTF_KIND_FLOAT type with:
1726 * - *name* - non-empty, non-NULL type name;
1727 * - *sz* - size of the type, in bytes;
1728 * Returns:
1729 * - >0, type ID of newly added BTF type;
1730 * - <0, on error.
1731 */
btf__add_float(struct btf * btf,const char * name,size_t byte_sz)1732 int btf__add_float(struct btf *btf, const char *name, size_t byte_sz)
1733 {
1734 struct btf_type *t;
1735 int sz, name_off;
1736
1737 /* non-empty name */
1738 if (!name || !name[0])
1739 return -EINVAL;
1740
1741 /* byte_sz must be one of the explicitly allowed values */
1742 if (byte_sz != 2 && byte_sz != 4 && byte_sz != 8 && byte_sz != 12 &&
1743 byte_sz != 16)
1744 return -EINVAL;
1745
1746 if (btf_ensure_modifiable(btf))
1747 return -ENOMEM;
1748
1749 sz = sizeof(struct btf_type);
1750 t = btf_add_type_mem(btf, sz);
1751 if (!t)
1752 return -ENOMEM;
1753
1754 name_off = btf__add_str(btf, name);
1755 if (name_off < 0)
1756 return name_off;
1757
1758 t->name_off = name_off;
1759 t->info = btf_type_info(BTF_KIND_FLOAT, 0, 0);
1760 t->size = byte_sz;
1761
1762 return btf_commit_type(btf, sz);
1763 }
1764
1765 /* it's completely legal to append BTF types with type IDs pointing forward to
1766 * types that haven't been appended yet, so we only make sure that id looks
1767 * sane, we can't guarantee that ID will always be valid
1768 */
validate_type_id(int id)1769 static int validate_type_id(int id)
1770 {
1771 if (id < 0 || id > BTF_MAX_NR_TYPES)
1772 return -EINVAL;
1773 return 0;
1774 }
1775
1776 /* generic append function for PTR, TYPEDEF, CONST/VOLATILE/RESTRICT */
btf_add_ref_kind(struct btf * btf,int kind,const char * name,int ref_type_id)1777 static int btf_add_ref_kind(struct btf *btf, int kind, const char *name, int ref_type_id)
1778 {
1779 struct btf_type *t;
1780 int sz, name_off = 0;
1781
1782 if (validate_type_id(ref_type_id))
1783 return -EINVAL;
1784
1785 if (btf_ensure_modifiable(btf))
1786 return -ENOMEM;
1787
1788 sz = sizeof(struct btf_type);
1789 t = btf_add_type_mem(btf, sz);
1790 if (!t)
1791 return -ENOMEM;
1792
1793 if (name && name[0]) {
1794 name_off = btf__add_str(btf, name);
1795 if (name_off < 0)
1796 return name_off;
1797 }
1798
1799 t->name_off = name_off;
1800 t->info = btf_type_info(kind, 0, 0);
1801 t->type = ref_type_id;
1802
1803 return btf_commit_type(btf, sz);
1804 }
1805
1806 /*
1807 * Append new BTF_KIND_PTR type with:
1808 * - *ref_type_id* - referenced type ID, it might not exist yet;
1809 * Returns:
1810 * - >0, type ID of newly added BTF type;
1811 * - <0, on error.
1812 */
btf__add_ptr(struct btf * btf,int ref_type_id)1813 int btf__add_ptr(struct btf *btf, int ref_type_id)
1814 {
1815 return btf_add_ref_kind(btf, BTF_KIND_PTR, NULL, ref_type_id);
1816 }
1817
1818 /*
1819 * Append new BTF_KIND_ARRAY type with:
1820 * - *index_type_id* - type ID of the type describing array index;
1821 * - *elem_type_id* - type ID of the type describing array element;
1822 * - *nr_elems* - the size of the array;
1823 * Returns:
1824 * - >0, type ID of newly added BTF type;
1825 * - <0, on error.
1826 */
btf__add_array(struct btf * btf,int index_type_id,int elem_type_id,__u32 nr_elems)1827 int btf__add_array(struct btf *btf, int index_type_id, int elem_type_id, __u32 nr_elems)
1828 {
1829 struct btf_type *t;
1830 struct btf_array *a;
1831 int sz;
1832
1833 if (validate_type_id(index_type_id) || validate_type_id(elem_type_id))
1834 return -EINVAL;
1835
1836 if (btf_ensure_modifiable(btf))
1837 return -ENOMEM;
1838
1839 sz = sizeof(struct btf_type) + sizeof(struct btf_array);
1840 t = btf_add_type_mem(btf, sz);
1841 if (!t)
1842 return -ENOMEM;
1843
1844 t->name_off = 0;
1845 t->info = btf_type_info(BTF_KIND_ARRAY, 0, 0);
1846 t->size = 0;
1847
1848 a = btf_array(t);
1849 a->type = elem_type_id;
1850 a->index_type = index_type_id;
1851 a->nelems = nr_elems;
1852
1853 return btf_commit_type(btf, sz);
1854 }
1855
1856 /* generic STRUCT/UNION append function */
btf_add_composite(struct btf * btf,int kind,const char * name,__u32 bytes_sz)1857 static int btf_add_composite(struct btf *btf, int kind, const char *name, __u32 bytes_sz)
1858 {
1859 struct btf_type *t;
1860 int sz, name_off = 0;
1861
1862 if (btf_ensure_modifiable(btf))
1863 return -ENOMEM;
1864
1865 sz = sizeof(struct btf_type);
1866 t = btf_add_type_mem(btf, sz);
1867 if (!t)
1868 return -ENOMEM;
1869
1870 if (name && name[0]) {
1871 name_off = btf__add_str(btf, name);
1872 if (name_off < 0)
1873 return name_off;
1874 }
1875
1876 /* start out with vlen=0 and no kflag; this will be adjusted when
1877 * adding each member
1878 */
1879 t->name_off = name_off;
1880 t->info = btf_type_info(kind, 0, 0);
1881 t->size = bytes_sz;
1882
1883 return btf_commit_type(btf, sz);
1884 }
1885
1886 /*
1887 * Append new BTF_KIND_STRUCT type with:
1888 * - *name* - name of the struct, can be NULL or empty for anonymous structs;
1889 * - *byte_sz* - size of the struct, in bytes;
1890 *
1891 * Struct initially has no fields in it. Fields can be added by
1892 * btf__add_field() right after btf__add_struct() succeeds.
1893 *
1894 * Returns:
1895 * - >0, type ID of newly added BTF type;
1896 * - <0, on error.
1897 */
btf__add_struct(struct btf * btf,const char * name,__u32 byte_sz)1898 int btf__add_struct(struct btf *btf, const char *name, __u32 byte_sz)
1899 {
1900 return btf_add_composite(btf, BTF_KIND_STRUCT, name, byte_sz);
1901 }
1902
1903 /*
1904 * Append new BTF_KIND_UNION type with:
1905 * - *name* - name of the union, can be NULL or empty for anonymous union;
1906 * - *byte_sz* - size of the union, in bytes;
1907 *
1908 * Union initially has no fields in it. Fields can be added by
1909 * btf__add_field() right after btf__add_union() succeeds. All fields
1910 * should have *bit_offset* of 0.
1911 *
1912 * Returns:
1913 * - >0, type ID of newly added BTF type;
1914 * - <0, on error.
1915 */
btf__add_union(struct btf * btf,const char * name,__u32 byte_sz)1916 int btf__add_union(struct btf *btf, const char *name, __u32 byte_sz)
1917 {
1918 return btf_add_composite(btf, BTF_KIND_UNION, name, byte_sz);
1919 }
1920
btf_last_type(struct btf * btf)1921 static struct btf_type *btf_last_type(struct btf *btf)
1922 {
1923 return btf_type_by_id(btf, btf__get_nr_types(btf));
1924 }
1925
1926 /*
1927 * Append new field for the current STRUCT/UNION type with:
1928 * - *name* - name of the field, can be NULL or empty for anonymous field;
1929 * - *type_id* - type ID for the type describing field type;
1930 * - *bit_offset* - bit offset of the start of the field within struct/union;
1931 * - *bit_size* - bit size of a bitfield, 0 for non-bitfield fields;
1932 * Returns:
1933 * - 0, on success;
1934 * - <0, on error.
1935 */
btf__add_field(struct btf * btf,const char * name,int type_id,__u32 bit_offset,__u32 bit_size)1936 int btf__add_field(struct btf *btf, const char *name, int type_id,
1937 __u32 bit_offset, __u32 bit_size)
1938 {
1939 struct btf_type *t;
1940 struct btf_member *m;
1941 bool is_bitfield;
1942 int sz, name_off = 0;
1943
1944 /* last type should be union/struct */
1945 if (btf->nr_types == 0)
1946 return -EINVAL;
1947 t = btf_last_type(btf);
1948 if (!btf_is_composite(t))
1949 return -EINVAL;
1950
1951 if (validate_type_id(type_id))
1952 return -EINVAL;
1953 /* best-effort bit field offset/size enforcement */
1954 is_bitfield = bit_size || (bit_offset % 8 != 0);
1955 if (is_bitfield && (bit_size == 0 || bit_size > 255 || bit_offset > 0xffffff))
1956 return -EINVAL;
1957
1958 /* only offset 0 is allowed for unions */
1959 if (btf_is_union(t) && bit_offset)
1960 return -EINVAL;
1961
1962 /* decompose and invalidate raw data */
1963 if (btf_ensure_modifiable(btf))
1964 return -ENOMEM;
1965
1966 sz = sizeof(struct btf_member);
1967 m = btf_add_type_mem(btf, sz);
1968 if (!m)
1969 return -ENOMEM;
1970
1971 if (name && name[0]) {
1972 name_off = btf__add_str(btf, name);
1973 if (name_off < 0)
1974 return name_off;
1975 }
1976
1977 m->name_off = name_off;
1978 m->type = type_id;
1979 m->offset = bit_offset | (bit_size << 24);
1980
1981 /* btf_add_type_mem can invalidate t pointer */
1982 t = btf_last_type(btf);
1983 /* update parent type's vlen and kflag */
1984 t->info = btf_type_info(btf_kind(t), btf_vlen(t) + 1, is_bitfield || btf_kflag(t));
1985
1986 btf->hdr->type_len += sz;
1987 btf->hdr->str_off += sz;
1988 return 0;
1989 }
1990
1991 /*
1992 * Append new BTF_KIND_ENUM type with:
1993 * - *name* - name of the enum, can be NULL or empty for anonymous enums;
1994 * - *byte_sz* - size of the enum, in bytes.
1995 *
1996 * Enum initially has no enum values in it (and corresponds to enum forward
1997 * declaration). Enumerator values can be added by btf__add_enum_value()
1998 * immediately after btf__add_enum() succeeds.
1999 *
2000 * Returns:
2001 * - >0, type ID of newly added BTF type;
2002 * - <0, on error.
2003 */
btf__add_enum(struct btf * btf,const char * name,__u32 byte_sz)2004 int btf__add_enum(struct btf *btf, const char *name, __u32 byte_sz)
2005 {
2006 struct btf_type *t;
2007 int sz, name_off = 0;
2008
2009 /* byte_sz must be power of 2 */
2010 if (!byte_sz || (byte_sz & (byte_sz - 1)) || byte_sz > 8)
2011 return -EINVAL;
2012
2013 if (btf_ensure_modifiable(btf))
2014 return -ENOMEM;
2015
2016 sz = sizeof(struct btf_type);
2017 t = btf_add_type_mem(btf, sz);
2018 if (!t)
2019 return -ENOMEM;
2020
2021 if (name && name[0]) {
2022 name_off = btf__add_str(btf, name);
2023 if (name_off < 0)
2024 return name_off;
2025 }
2026
2027 /* start out with vlen=0; it will be adjusted when adding enum values */
2028 t->name_off = name_off;
2029 t->info = btf_type_info(BTF_KIND_ENUM, 0, 0);
2030 t->size = byte_sz;
2031
2032 return btf_commit_type(btf, sz);
2033 }
2034
2035 /*
2036 * Append new enum value for the current ENUM type with:
2037 * - *name* - name of the enumerator value, can't be NULL or empty;
2038 * - *value* - integer value corresponding to enum value *name*;
2039 * Returns:
2040 * - 0, on success;
2041 * - <0, on error.
2042 */
btf__add_enum_value(struct btf * btf,const char * name,__s64 value)2043 int btf__add_enum_value(struct btf *btf, const char *name, __s64 value)
2044 {
2045 struct btf_type *t;
2046 struct btf_enum *v;
2047 int sz, name_off;
2048
2049 /* last type should be BTF_KIND_ENUM */
2050 if (btf->nr_types == 0)
2051 return -EINVAL;
2052 t = btf_last_type(btf);
2053 if (!btf_is_enum(t))
2054 return -EINVAL;
2055
2056 /* non-empty name */
2057 if (!name || !name[0])
2058 return -EINVAL;
2059 if (value < INT_MIN || value > UINT_MAX)
2060 return -E2BIG;
2061
2062 /* decompose and invalidate raw data */
2063 if (btf_ensure_modifiable(btf))
2064 return -ENOMEM;
2065
2066 sz = sizeof(struct btf_enum);
2067 v = btf_add_type_mem(btf, sz);
2068 if (!v)
2069 return -ENOMEM;
2070
2071 name_off = btf__add_str(btf, name);
2072 if (name_off < 0)
2073 return name_off;
2074
2075 v->name_off = name_off;
2076 v->val = value;
2077
2078 /* update parent type's vlen */
2079 t = btf_last_type(btf);
2080 btf_type_inc_vlen(t);
2081
2082 btf->hdr->type_len += sz;
2083 btf->hdr->str_off += sz;
2084 return 0;
2085 }
2086
2087 /*
2088 * Append new BTF_KIND_FWD type with:
2089 * - *name*, non-empty/non-NULL name;
2090 * - *fwd_kind*, kind of forward declaration, one of BTF_FWD_STRUCT,
2091 * BTF_FWD_UNION, or BTF_FWD_ENUM;
2092 * Returns:
2093 * - >0, type ID of newly added BTF type;
2094 * - <0, on error.
2095 */
btf__add_fwd(struct btf * btf,const char * name,enum btf_fwd_kind fwd_kind)2096 int btf__add_fwd(struct btf *btf, const char *name, enum btf_fwd_kind fwd_kind)
2097 {
2098 if (!name || !name[0])
2099 return -EINVAL;
2100
2101 switch (fwd_kind) {
2102 case BTF_FWD_STRUCT:
2103 case BTF_FWD_UNION: {
2104 struct btf_type *t;
2105 int id;
2106
2107 id = btf_add_ref_kind(btf, BTF_KIND_FWD, name, 0);
2108 if (id <= 0)
2109 return id;
2110 t = btf_type_by_id(btf, id);
2111 t->info = btf_type_info(BTF_KIND_FWD, 0, fwd_kind == BTF_FWD_UNION);
2112 return id;
2113 }
2114 case BTF_FWD_ENUM:
2115 /* enum forward in BTF currently is just an enum with no enum
2116 * values; we also assume a standard 4-byte size for it
2117 */
2118 return btf__add_enum(btf, name, sizeof(int));
2119 default:
2120 return -EINVAL;
2121 }
2122 }
2123
2124 /*
2125 * Append new BTF_KING_TYPEDEF type with:
2126 * - *name*, non-empty/non-NULL name;
2127 * - *ref_type_id* - referenced type ID, it might not exist yet;
2128 * Returns:
2129 * - >0, type ID of newly added BTF type;
2130 * - <0, on error.
2131 */
btf__add_typedef(struct btf * btf,const char * name,int ref_type_id)2132 int btf__add_typedef(struct btf *btf, const char *name, int ref_type_id)
2133 {
2134 if (!name || !name[0])
2135 return -EINVAL;
2136
2137 return btf_add_ref_kind(btf, BTF_KIND_TYPEDEF, name, ref_type_id);
2138 }
2139
2140 /*
2141 * Append new BTF_KIND_VOLATILE type with:
2142 * - *ref_type_id* - referenced type ID, it might not exist yet;
2143 * Returns:
2144 * - >0, type ID of newly added BTF type;
2145 * - <0, on error.
2146 */
btf__add_volatile(struct btf * btf,int ref_type_id)2147 int btf__add_volatile(struct btf *btf, int ref_type_id)
2148 {
2149 return btf_add_ref_kind(btf, BTF_KIND_VOLATILE, NULL, ref_type_id);
2150 }
2151
2152 /*
2153 * Append new BTF_KIND_CONST type with:
2154 * - *ref_type_id* - referenced type ID, it might not exist yet;
2155 * Returns:
2156 * - >0, type ID of newly added BTF type;
2157 * - <0, on error.
2158 */
btf__add_const(struct btf * btf,int ref_type_id)2159 int btf__add_const(struct btf *btf, int ref_type_id)
2160 {
2161 return btf_add_ref_kind(btf, BTF_KIND_CONST, NULL, ref_type_id);
2162 }
2163
2164 /*
2165 * Append new BTF_KIND_RESTRICT type with:
2166 * - *ref_type_id* - referenced type ID, it might not exist yet;
2167 * Returns:
2168 * - >0, type ID of newly added BTF type;
2169 * - <0, on error.
2170 */
btf__add_restrict(struct btf * btf,int ref_type_id)2171 int btf__add_restrict(struct btf *btf, int ref_type_id)
2172 {
2173 return btf_add_ref_kind(btf, BTF_KIND_RESTRICT, NULL, ref_type_id);
2174 }
2175
2176 /*
2177 * Append new BTF_KIND_FUNC type with:
2178 * - *name*, non-empty/non-NULL name;
2179 * - *proto_type_id* - FUNC_PROTO's type ID, it might not exist yet;
2180 * Returns:
2181 * - >0, type ID of newly added BTF type;
2182 * - <0, on error.
2183 */
btf__add_func(struct btf * btf,const char * name,enum btf_func_linkage linkage,int proto_type_id)2184 int btf__add_func(struct btf *btf, const char *name,
2185 enum btf_func_linkage linkage, int proto_type_id)
2186 {
2187 int id;
2188
2189 if (!name || !name[0])
2190 return -EINVAL;
2191 if (linkage != BTF_FUNC_STATIC && linkage != BTF_FUNC_GLOBAL &&
2192 linkage != BTF_FUNC_EXTERN)
2193 return -EINVAL;
2194
2195 id = btf_add_ref_kind(btf, BTF_KIND_FUNC, name, proto_type_id);
2196 if (id > 0) {
2197 struct btf_type *t = btf_type_by_id(btf, id);
2198
2199 t->info = btf_type_info(BTF_KIND_FUNC, linkage, 0);
2200 }
2201 return id;
2202 }
2203
2204 /*
2205 * Append new BTF_KIND_FUNC_PROTO with:
2206 * - *ret_type_id* - type ID for return result of a function.
2207 *
2208 * Function prototype initially has no arguments, but they can be added by
2209 * btf__add_func_param() one by one, immediately after
2210 * btf__add_func_proto() succeeded.
2211 *
2212 * Returns:
2213 * - >0, type ID of newly added BTF type;
2214 * - <0, on error.
2215 */
btf__add_func_proto(struct btf * btf,int ret_type_id)2216 int btf__add_func_proto(struct btf *btf, int ret_type_id)
2217 {
2218 struct btf_type *t;
2219 int sz;
2220
2221 if (validate_type_id(ret_type_id))
2222 return -EINVAL;
2223
2224 if (btf_ensure_modifiable(btf))
2225 return -ENOMEM;
2226
2227 sz = sizeof(struct btf_type);
2228 t = btf_add_type_mem(btf, sz);
2229 if (!t)
2230 return -ENOMEM;
2231
2232 /* start out with vlen=0; this will be adjusted when adding enum
2233 * values, if necessary
2234 */
2235 t->name_off = 0;
2236 t->info = btf_type_info(BTF_KIND_FUNC_PROTO, 0, 0);
2237 t->type = ret_type_id;
2238
2239 return btf_commit_type(btf, sz);
2240 }
2241
2242 /*
2243 * Append new function parameter for current FUNC_PROTO type with:
2244 * - *name* - parameter name, can be NULL or empty;
2245 * - *type_id* - type ID describing the type of the parameter.
2246 * Returns:
2247 * - 0, on success;
2248 * - <0, on error.
2249 */
btf__add_func_param(struct btf * btf,const char * name,int type_id)2250 int btf__add_func_param(struct btf *btf, const char *name, int type_id)
2251 {
2252 struct btf_type *t;
2253 struct btf_param *p;
2254 int sz, name_off = 0;
2255
2256 if (validate_type_id(type_id))
2257 return -EINVAL;
2258
2259 /* last type should be BTF_KIND_FUNC_PROTO */
2260 if (btf->nr_types == 0)
2261 return -EINVAL;
2262 t = btf_last_type(btf);
2263 if (!btf_is_func_proto(t))
2264 return -EINVAL;
2265
2266 /* decompose and invalidate raw data */
2267 if (btf_ensure_modifiable(btf))
2268 return -ENOMEM;
2269
2270 sz = sizeof(struct btf_param);
2271 p = btf_add_type_mem(btf, sz);
2272 if (!p)
2273 return -ENOMEM;
2274
2275 if (name && name[0]) {
2276 name_off = btf__add_str(btf, name);
2277 if (name_off < 0)
2278 return name_off;
2279 }
2280
2281 p->name_off = name_off;
2282 p->type = type_id;
2283
2284 /* update parent type's vlen */
2285 t = btf_last_type(btf);
2286 btf_type_inc_vlen(t);
2287
2288 btf->hdr->type_len += sz;
2289 btf->hdr->str_off += sz;
2290 return 0;
2291 }
2292
2293 /*
2294 * Append new BTF_KIND_VAR type with:
2295 * - *name* - non-empty/non-NULL name;
2296 * - *linkage* - variable linkage, one of BTF_VAR_STATIC,
2297 * BTF_VAR_GLOBAL_ALLOCATED, or BTF_VAR_GLOBAL_EXTERN;
2298 * - *type_id* - type ID of the type describing the type of the variable.
2299 * Returns:
2300 * - >0, type ID of newly added BTF type;
2301 * - <0, on error.
2302 */
btf__add_var(struct btf * btf,const char * name,int linkage,int type_id)2303 int btf__add_var(struct btf *btf, const char *name, int linkage, int type_id)
2304 {
2305 struct btf_type *t;
2306 struct btf_var *v;
2307 int sz, name_off;
2308
2309 /* non-empty name */
2310 if (!name || !name[0])
2311 return -EINVAL;
2312 if (linkage != BTF_VAR_STATIC && linkage != BTF_VAR_GLOBAL_ALLOCATED &&
2313 linkage != BTF_VAR_GLOBAL_EXTERN)
2314 return -EINVAL;
2315 if (validate_type_id(type_id))
2316 return -EINVAL;
2317
2318 /* deconstruct BTF, if necessary, and invalidate raw_data */
2319 if (btf_ensure_modifiable(btf))
2320 return -ENOMEM;
2321
2322 sz = sizeof(struct btf_type) + sizeof(struct btf_var);
2323 t = btf_add_type_mem(btf, sz);
2324 if (!t)
2325 return -ENOMEM;
2326
2327 name_off = btf__add_str(btf, name);
2328 if (name_off < 0)
2329 return name_off;
2330
2331 t->name_off = name_off;
2332 t->info = btf_type_info(BTF_KIND_VAR, 0, 0);
2333 t->type = type_id;
2334
2335 v = btf_var(t);
2336 v->linkage = linkage;
2337
2338 return btf_commit_type(btf, sz);
2339 }
2340
2341 /*
2342 * Append new BTF_KIND_DATASEC type with:
2343 * - *name* - non-empty/non-NULL name;
2344 * - *byte_sz* - data section size, in bytes.
2345 *
2346 * Data section is initially empty. Variables info can be added with
2347 * btf__add_datasec_var_info() calls, after btf__add_datasec() succeeds.
2348 *
2349 * Returns:
2350 * - >0, type ID of newly added BTF type;
2351 * - <0, on error.
2352 */
btf__add_datasec(struct btf * btf,const char * name,__u32 byte_sz)2353 int btf__add_datasec(struct btf *btf, const char *name, __u32 byte_sz)
2354 {
2355 struct btf_type *t;
2356 int sz, name_off;
2357
2358 /* non-empty name */
2359 if (!name || !name[0])
2360 return -EINVAL;
2361
2362 if (btf_ensure_modifiable(btf))
2363 return -ENOMEM;
2364
2365 sz = sizeof(struct btf_type);
2366 t = btf_add_type_mem(btf, sz);
2367 if (!t)
2368 return -ENOMEM;
2369
2370 name_off = btf__add_str(btf, name);
2371 if (name_off < 0)
2372 return name_off;
2373
2374 /* start with vlen=0, which will be update as var_secinfos are added */
2375 t->name_off = name_off;
2376 t->info = btf_type_info(BTF_KIND_DATASEC, 0, 0);
2377 t->size = byte_sz;
2378
2379 return btf_commit_type(btf, sz);
2380 }
2381
2382 /*
2383 * Append new data section variable information entry for current DATASEC type:
2384 * - *var_type_id* - type ID, describing type of the variable;
2385 * - *offset* - variable offset within data section, in bytes;
2386 * - *byte_sz* - variable size, in bytes.
2387 *
2388 * Returns:
2389 * - 0, on success;
2390 * - <0, on error.
2391 */
btf__add_datasec_var_info(struct btf * btf,int var_type_id,__u32 offset,__u32 byte_sz)2392 int btf__add_datasec_var_info(struct btf *btf, int var_type_id, __u32 offset, __u32 byte_sz)
2393 {
2394 struct btf_type *t;
2395 struct btf_var_secinfo *v;
2396 int sz;
2397
2398 /* last type should be BTF_KIND_DATASEC */
2399 if (btf->nr_types == 0)
2400 return -EINVAL;
2401 t = btf_last_type(btf);
2402 if (!btf_is_datasec(t))
2403 return -EINVAL;
2404
2405 if (validate_type_id(var_type_id))
2406 return -EINVAL;
2407
2408 /* decompose and invalidate raw data */
2409 if (btf_ensure_modifiable(btf))
2410 return -ENOMEM;
2411
2412 sz = sizeof(struct btf_var_secinfo);
2413 v = btf_add_type_mem(btf, sz);
2414 if (!v)
2415 return -ENOMEM;
2416
2417 v->type = var_type_id;
2418 v->offset = offset;
2419 v->size = byte_sz;
2420
2421 /* update parent type's vlen */
2422 t = btf_last_type(btf);
2423 btf_type_inc_vlen(t);
2424
2425 btf->hdr->type_len += sz;
2426 btf->hdr->str_off += sz;
2427 return 0;
2428 }
2429
2430 struct btf_ext_sec_setup_param {
2431 __u32 off;
2432 __u32 len;
2433 __u32 min_rec_size;
2434 struct btf_ext_info *ext_info;
2435 const char *desc;
2436 };
2437
btf_ext_setup_info(struct btf_ext * btf_ext,struct btf_ext_sec_setup_param * ext_sec)2438 static int btf_ext_setup_info(struct btf_ext *btf_ext,
2439 struct btf_ext_sec_setup_param *ext_sec)
2440 {
2441 const struct btf_ext_info_sec *sinfo;
2442 struct btf_ext_info *ext_info;
2443 __u32 info_left, record_size;
2444 /* The start of the info sec (including the __u32 record_size). */
2445 void *info;
2446
2447 if (ext_sec->len == 0)
2448 return 0;
2449
2450 if (ext_sec->off & 0x03) {
2451 pr_debug(".BTF.ext %s section is not aligned to 4 bytes\n",
2452 ext_sec->desc);
2453 return -EINVAL;
2454 }
2455
2456 info = btf_ext->data + btf_ext->hdr->hdr_len + ext_sec->off;
2457 info_left = ext_sec->len;
2458
2459 if (btf_ext->data + btf_ext->data_size < info + ext_sec->len) {
2460 pr_debug("%s section (off:%u len:%u) is beyond the end of the ELF section .BTF.ext\n",
2461 ext_sec->desc, ext_sec->off, ext_sec->len);
2462 return -EINVAL;
2463 }
2464
2465 /* At least a record size */
2466 if (info_left < sizeof(__u32)) {
2467 pr_debug(".BTF.ext %s record size not found\n", ext_sec->desc);
2468 return -EINVAL;
2469 }
2470
2471 /* The record size needs to meet the minimum standard */
2472 record_size = *(__u32 *)info;
2473 if (record_size < ext_sec->min_rec_size ||
2474 record_size & 0x03) {
2475 pr_debug("%s section in .BTF.ext has invalid record size %u\n",
2476 ext_sec->desc, record_size);
2477 return -EINVAL;
2478 }
2479
2480 sinfo = info + sizeof(__u32);
2481 info_left -= sizeof(__u32);
2482
2483 /* If no records, return failure now so .BTF.ext won't be used. */
2484 if (!info_left) {
2485 pr_debug("%s section in .BTF.ext has no records", ext_sec->desc);
2486 return -EINVAL;
2487 }
2488
2489 while (info_left) {
2490 unsigned int sec_hdrlen = sizeof(struct btf_ext_info_sec);
2491 __u64 total_record_size;
2492 __u32 num_records;
2493
2494 if (info_left < sec_hdrlen) {
2495 pr_debug("%s section header is not found in .BTF.ext\n",
2496 ext_sec->desc);
2497 return -EINVAL;
2498 }
2499
2500 num_records = sinfo->num_info;
2501 if (num_records == 0) {
2502 pr_debug("%s section has incorrect num_records in .BTF.ext\n",
2503 ext_sec->desc);
2504 return -EINVAL;
2505 }
2506
2507 total_record_size = sec_hdrlen +
2508 (__u64)num_records * record_size;
2509 if (info_left < total_record_size) {
2510 pr_debug("%s section has incorrect num_records in .BTF.ext\n",
2511 ext_sec->desc);
2512 return -EINVAL;
2513 }
2514
2515 info_left -= total_record_size;
2516 sinfo = (void *)sinfo + total_record_size;
2517 }
2518
2519 ext_info = ext_sec->ext_info;
2520 ext_info->len = ext_sec->len - sizeof(__u32);
2521 ext_info->rec_size = record_size;
2522 ext_info->info = info + sizeof(__u32);
2523
2524 return 0;
2525 }
2526
btf_ext_setup_func_info(struct btf_ext * btf_ext)2527 static int btf_ext_setup_func_info(struct btf_ext *btf_ext)
2528 {
2529 struct btf_ext_sec_setup_param param = {
2530 .off = btf_ext->hdr->func_info_off,
2531 .len = btf_ext->hdr->func_info_len,
2532 .min_rec_size = sizeof(struct bpf_func_info_min),
2533 .ext_info = &btf_ext->func_info,
2534 .desc = "func_info"
2535 };
2536
2537 return btf_ext_setup_info(btf_ext, ¶m);
2538 }
2539
btf_ext_setup_line_info(struct btf_ext * btf_ext)2540 static int btf_ext_setup_line_info(struct btf_ext *btf_ext)
2541 {
2542 struct btf_ext_sec_setup_param param = {
2543 .off = btf_ext->hdr->line_info_off,
2544 .len = btf_ext->hdr->line_info_len,
2545 .min_rec_size = sizeof(struct bpf_line_info_min),
2546 .ext_info = &btf_ext->line_info,
2547 .desc = "line_info",
2548 };
2549
2550 return btf_ext_setup_info(btf_ext, ¶m);
2551 }
2552
btf_ext_setup_core_relos(struct btf_ext * btf_ext)2553 static int btf_ext_setup_core_relos(struct btf_ext *btf_ext)
2554 {
2555 struct btf_ext_sec_setup_param param = {
2556 .off = btf_ext->hdr->core_relo_off,
2557 .len = btf_ext->hdr->core_relo_len,
2558 .min_rec_size = sizeof(struct bpf_core_relo),
2559 .ext_info = &btf_ext->core_relo_info,
2560 .desc = "core_relo",
2561 };
2562
2563 return btf_ext_setup_info(btf_ext, ¶m);
2564 }
2565
btf_ext_parse_hdr(__u8 * data,__u32 data_size)2566 static int btf_ext_parse_hdr(__u8 *data, __u32 data_size)
2567 {
2568 const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
2569
2570 if (data_size < offsetofend(struct btf_ext_header, hdr_len) ||
2571 data_size < hdr->hdr_len) {
2572 pr_debug("BTF.ext header not found");
2573 return -EINVAL;
2574 }
2575
2576 if (hdr->magic == bswap_16(BTF_MAGIC)) {
2577 pr_warn("BTF.ext in non-native endianness is not supported\n");
2578 return -ENOTSUP;
2579 } else if (hdr->magic != BTF_MAGIC) {
2580 pr_debug("Invalid BTF.ext magic:%x\n", hdr->magic);
2581 return -EINVAL;
2582 }
2583
2584 if (hdr->version != BTF_VERSION) {
2585 pr_debug("Unsupported BTF.ext version:%u\n", hdr->version);
2586 return -ENOTSUP;
2587 }
2588
2589 if (hdr->flags) {
2590 pr_debug("Unsupported BTF.ext flags:%x\n", hdr->flags);
2591 return -ENOTSUP;
2592 }
2593
2594 if (data_size == hdr->hdr_len) {
2595 pr_debug("BTF.ext has no data\n");
2596 return -EINVAL;
2597 }
2598
2599 return 0;
2600 }
2601
btf_ext__free(struct btf_ext * btf_ext)2602 void btf_ext__free(struct btf_ext *btf_ext)
2603 {
2604 if (IS_ERR_OR_NULL(btf_ext))
2605 return;
2606 free(btf_ext->data);
2607 free(btf_ext);
2608 }
2609
btf_ext__new(__u8 * data,__u32 size)2610 struct btf_ext *btf_ext__new(__u8 *data, __u32 size)
2611 {
2612 struct btf_ext *btf_ext;
2613 int err;
2614
2615 err = btf_ext_parse_hdr(data, size);
2616 if (err)
2617 return ERR_PTR(err);
2618
2619 btf_ext = calloc(1, sizeof(struct btf_ext));
2620 if (!btf_ext)
2621 return ERR_PTR(-ENOMEM);
2622
2623 btf_ext->data_size = size;
2624 btf_ext->data = malloc(size);
2625 if (!btf_ext->data) {
2626 err = -ENOMEM;
2627 goto done;
2628 }
2629 memcpy(btf_ext->data, data, size);
2630
2631 if (btf_ext->hdr->hdr_len <
2632 offsetofend(struct btf_ext_header, line_info_len))
2633 goto done;
2634 err = btf_ext_setup_func_info(btf_ext);
2635 if (err)
2636 goto done;
2637
2638 err = btf_ext_setup_line_info(btf_ext);
2639 if (err)
2640 goto done;
2641
2642 if (btf_ext->hdr->hdr_len < offsetofend(struct btf_ext_header, core_relo_len))
2643 goto done;
2644 err = btf_ext_setup_core_relos(btf_ext);
2645 if (err)
2646 goto done;
2647
2648 done:
2649 if (err) {
2650 btf_ext__free(btf_ext);
2651 return ERR_PTR(err);
2652 }
2653
2654 return btf_ext;
2655 }
2656
btf_ext__get_raw_data(const struct btf_ext * btf_ext,__u32 * size)2657 const void *btf_ext__get_raw_data(const struct btf_ext *btf_ext, __u32 *size)
2658 {
2659 *size = btf_ext->data_size;
2660 return btf_ext->data;
2661 }
2662
btf_ext_reloc_info(const struct btf * btf,const struct btf_ext_info * ext_info,const char * sec_name,__u32 insns_cnt,void ** info,__u32 * cnt)2663 static int btf_ext_reloc_info(const struct btf *btf,
2664 const struct btf_ext_info *ext_info,
2665 const char *sec_name, __u32 insns_cnt,
2666 void **info, __u32 *cnt)
2667 {
2668 __u32 sec_hdrlen = sizeof(struct btf_ext_info_sec);
2669 __u32 i, record_size, existing_len, records_len;
2670 struct btf_ext_info_sec *sinfo;
2671 const char *info_sec_name;
2672 __u64 remain_len;
2673 void *data;
2674
2675 record_size = ext_info->rec_size;
2676 sinfo = ext_info->info;
2677 remain_len = ext_info->len;
2678 while (remain_len > 0) {
2679 records_len = sinfo->num_info * record_size;
2680 info_sec_name = btf__name_by_offset(btf, sinfo->sec_name_off);
2681 if (strcmp(info_sec_name, sec_name)) {
2682 remain_len -= sec_hdrlen + records_len;
2683 sinfo = (void *)sinfo + sec_hdrlen + records_len;
2684 continue;
2685 }
2686
2687 existing_len = (*cnt) * record_size;
2688 data = realloc(*info, existing_len + records_len);
2689 if (!data)
2690 return -ENOMEM;
2691
2692 memcpy(data + existing_len, sinfo->data, records_len);
2693 /* adjust insn_off only, the rest data will be passed
2694 * to the kernel.
2695 */
2696 for (i = 0; i < sinfo->num_info; i++) {
2697 __u32 *insn_off;
2698
2699 insn_off = data + existing_len + (i * record_size);
2700 *insn_off = *insn_off / sizeof(struct bpf_insn) +
2701 insns_cnt;
2702 }
2703 *info = data;
2704 *cnt += sinfo->num_info;
2705 return 0;
2706 }
2707
2708 return -ENOENT;
2709 }
2710
btf_ext__reloc_func_info(const struct btf * btf,const struct btf_ext * btf_ext,const char * sec_name,__u32 insns_cnt,void ** func_info,__u32 * cnt)2711 int btf_ext__reloc_func_info(const struct btf *btf,
2712 const struct btf_ext *btf_ext,
2713 const char *sec_name, __u32 insns_cnt,
2714 void **func_info, __u32 *cnt)
2715 {
2716 return btf_ext_reloc_info(btf, &btf_ext->func_info, sec_name,
2717 insns_cnt, func_info, cnt);
2718 }
2719
btf_ext__reloc_line_info(const struct btf * btf,const struct btf_ext * btf_ext,const char * sec_name,__u32 insns_cnt,void ** line_info,__u32 * cnt)2720 int btf_ext__reloc_line_info(const struct btf *btf,
2721 const struct btf_ext *btf_ext,
2722 const char *sec_name, __u32 insns_cnt,
2723 void **line_info, __u32 *cnt)
2724 {
2725 return btf_ext_reloc_info(btf, &btf_ext->line_info, sec_name,
2726 insns_cnt, line_info, cnt);
2727 }
2728
btf_ext__func_info_rec_size(const struct btf_ext * btf_ext)2729 __u32 btf_ext__func_info_rec_size(const struct btf_ext *btf_ext)
2730 {
2731 return btf_ext->func_info.rec_size;
2732 }
2733
btf_ext__line_info_rec_size(const struct btf_ext * btf_ext)2734 __u32 btf_ext__line_info_rec_size(const struct btf_ext *btf_ext)
2735 {
2736 return btf_ext->line_info.rec_size;
2737 }
2738
2739 struct btf_dedup;
2740
2741 static struct btf_dedup *btf_dedup_new(struct btf *btf, struct btf_ext *btf_ext,
2742 const struct btf_dedup_opts *opts);
2743 static void btf_dedup_free(struct btf_dedup *d);
2744 static int btf_dedup_prep(struct btf_dedup *d);
2745 static int btf_dedup_strings(struct btf_dedup *d);
2746 static int btf_dedup_prim_types(struct btf_dedup *d);
2747 static int btf_dedup_struct_types(struct btf_dedup *d);
2748 static int btf_dedup_ref_types(struct btf_dedup *d);
2749 static int btf_dedup_compact_types(struct btf_dedup *d);
2750 static int btf_dedup_remap_types(struct btf_dedup *d);
2751
2752 /*
2753 * Deduplicate BTF types and strings.
2754 *
2755 * BTF dedup algorithm takes as an input `struct btf` representing `.BTF` ELF
2756 * section with all BTF type descriptors and string data. It overwrites that
2757 * memory in-place with deduplicated types and strings without any loss of
2758 * information. If optional `struct btf_ext` representing '.BTF.ext' ELF section
2759 * is provided, all the strings referenced from .BTF.ext section are honored
2760 * and updated to point to the right offsets after deduplication.
2761 *
2762 * If function returns with error, type/string data might be garbled and should
2763 * be discarded.
2764 *
2765 * More verbose and detailed description of both problem btf_dedup is solving,
2766 * as well as solution could be found at:
2767 * https://facebookmicrosites.github.io/bpf/blog/2018/11/14/btf-enhancement.html
2768 *
2769 * Problem description and justification
2770 * =====================================
2771 *
2772 * BTF type information is typically emitted either as a result of conversion
2773 * from DWARF to BTF or directly by compiler. In both cases, each compilation
2774 * unit contains information about a subset of all the types that are used
2775 * in an application. These subsets are frequently overlapping and contain a lot
2776 * of duplicated information when later concatenated together into a single
2777 * binary. This algorithm ensures that each unique type is represented by single
2778 * BTF type descriptor, greatly reducing resulting size of BTF data.
2779 *
2780 * Compilation unit isolation and subsequent duplication of data is not the only
2781 * problem. The same type hierarchy (e.g., struct and all the type that struct
2782 * references) in different compilation units can be represented in BTF to
2783 * various degrees of completeness (or, rather, incompleteness) due to
2784 * struct/union forward declarations.
2785 *
2786 * Let's take a look at an example, that we'll use to better understand the
2787 * problem (and solution). Suppose we have two compilation units, each using
2788 * same `struct S`, but each of them having incomplete type information about
2789 * struct's fields:
2790 *
2791 * // CU #1:
2792 * struct S;
2793 * struct A {
2794 * int a;
2795 * struct A* self;
2796 * struct S* parent;
2797 * };
2798 * struct B;
2799 * struct S {
2800 * struct A* a_ptr;
2801 * struct B* b_ptr;
2802 * };
2803 *
2804 * // CU #2:
2805 * struct S;
2806 * struct A;
2807 * struct B {
2808 * int b;
2809 * struct B* self;
2810 * struct S* parent;
2811 * };
2812 * struct S {
2813 * struct A* a_ptr;
2814 * struct B* b_ptr;
2815 * };
2816 *
2817 * In case of CU #1, BTF data will know only that `struct B` exist (but no
2818 * more), but will know the complete type information about `struct A`. While
2819 * for CU #2, it will know full type information about `struct B`, but will
2820 * only know about forward declaration of `struct A` (in BTF terms, it will
2821 * have `BTF_KIND_FWD` type descriptor with name `B`).
2822 *
2823 * This compilation unit isolation means that it's possible that there is no
2824 * single CU with complete type information describing structs `S`, `A`, and
2825 * `B`. Also, we might get tons of duplicated and redundant type information.
2826 *
2827 * Additional complication we need to keep in mind comes from the fact that
2828 * types, in general, can form graphs containing cycles, not just DAGs.
2829 *
2830 * While algorithm does deduplication, it also merges and resolves type
2831 * information (unless disabled throught `struct btf_opts`), whenever possible.
2832 * E.g., in the example above with two compilation units having partial type
2833 * information for structs `A` and `B`, the output of algorithm will emit
2834 * a single copy of each BTF type that describes structs `A`, `B`, and `S`
2835 * (as well as type information for `int` and pointers), as if they were defined
2836 * in a single compilation unit as:
2837 *
2838 * struct A {
2839 * int a;
2840 * struct A* self;
2841 * struct S* parent;
2842 * };
2843 * struct B {
2844 * int b;
2845 * struct B* self;
2846 * struct S* parent;
2847 * };
2848 * struct S {
2849 * struct A* a_ptr;
2850 * struct B* b_ptr;
2851 * };
2852 *
2853 * Algorithm summary
2854 * =================
2855 *
2856 * Algorithm completes its work in 6 separate passes:
2857 *
2858 * 1. Strings deduplication.
2859 * 2. Primitive types deduplication (int, enum, fwd).
2860 * 3. Struct/union types deduplication.
2861 * 4. Reference types deduplication (pointers, typedefs, arrays, funcs, func
2862 * protos, and const/volatile/restrict modifiers).
2863 * 5. Types compaction.
2864 * 6. Types remapping.
2865 *
2866 * Algorithm determines canonical type descriptor, which is a single
2867 * representative type for each truly unique type. This canonical type is the
2868 * one that will go into final deduplicated BTF type information. For
2869 * struct/unions, it is also the type that algorithm will merge additional type
2870 * information into (while resolving FWDs), as it discovers it from data in
2871 * other CUs. Each input BTF type eventually gets either mapped to itself, if
2872 * that type is canonical, or to some other type, if that type is equivalent
2873 * and was chosen as canonical representative. This mapping is stored in
2874 * `btf_dedup->map` array. This map is also used to record STRUCT/UNION that
2875 * FWD type got resolved to.
2876 *
2877 * To facilitate fast discovery of canonical types, we also maintain canonical
2878 * index (`btf_dedup->dedup_table`), which maps type descriptor's signature hash
2879 * (i.e., hashed kind, name, size, fields, etc) into a list of canonical types
2880 * that match that signature. With sufficiently good choice of type signature
2881 * hashing function, we can limit number of canonical types for each unique type
2882 * signature to a very small number, allowing to find canonical type for any
2883 * duplicated type very quickly.
2884 *
2885 * Struct/union deduplication is the most critical part and algorithm for
2886 * deduplicating structs/unions is described in greater details in comments for
2887 * `btf_dedup_is_equiv` function.
2888 */
btf__dedup(struct btf * btf,struct btf_ext * btf_ext,const struct btf_dedup_opts * opts)2889 int btf__dedup(struct btf *btf, struct btf_ext *btf_ext,
2890 const struct btf_dedup_opts *opts)
2891 {
2892 struct btf_dedup *d = btf_dedup_new(btf, btf_ext, opts);
2893 int err;
2894
2895 if (IS_ERR(d)) {
2896 pr_debug("btf_dedup_new failed: %ld", PTR_ERR(d));
2897 return -EINVAL;
2898 }
2899
2900 if (btf_ensure_modifiable(btf))
2901 return -ENOMEM;
2902
2903 err = btf_dedup_prep(d);
2904 if (err) {
2905 pr_debug("btf_dedup_prep failed:%d\n", err);
2906 goto done;
2907 }
2908 err = btf_dedup_strings(d);
2909 if (err < 0) {
2910 pr_debug("btf_dedup_strings failed:%d\n", err);
2911 goto done;
2912 }
2913 err = btf_dedup_prim_types(d);
2914 if (err < 0) {
2915 pr_debug("btf_dedup_prim_types failed:%d\n", err);
2916 goto done;
2917 }
2918 err = btf_dedup_struct_types(d);
2919 if (err < 0) {
2920 pr_debug("btf_dedup_struct_types failed:%d\n", err);
2921 goto done;
2922 }
2923 err = btf_dedup_ref_types(d);
2924 if (err < 0) {
2925 pr_debug("btf_dedup_ref_types failed:%d\n", err);
2926 goto done;
2927 }
2928 err = btf_dedup_compact_types(d);
2929 if (err < 0) {
2930 pr_debug("btf_dedup_compact_types failed:%d\n", err);
2931 goto done;
2932 }
2933 err = btf_dedup_remap_types(d);
2934 if (err < 0) {
2935 pr_debug("btf_dedup_remap_types failed:%d\n", err);
2936 goto done;
2937 }
2938
2939 done:
2940 btf_dedup_free(d);
2941 return err;
2942 }
2943
2944 #define BTF_UNPROCESSED_ID ((__u32)-1)
2945 #define BTF_IN_PROGRESS_ID ((__u32)-2)
2946
2947 struct btf_dedup {
2948 /* .BTF section to be deduped in-place */
2949 struct btf *btf;
2950 /*
2951 * Optional .BTF.ext section. When provided, any strings referenced
2952 * from it will be taken into account when deduping strings
2953 */
2954 struct btf_ext *btf_ext;
2955 /*
2956 * This is a map from any type's signature hash to a list of possible
2957 * canonical representative type candidates. Hash collisions are
2958 * ignored, so even types of various kinds can share same list of
2959 * candidates, which is fine because we rely on subsequent
2960 * btf_xxx_equal() checks to authoritatively verify type equality.
2961 */
2962 struct hashmap *dedup_table;
2963 /* Canonical types map */
2964 __u32 *map;
2965 /* Hypothetical mapping, used during type graph equivalence checks */
2966 __u32 *hypot_map;
2967 __u32 *hypot_list;
2968 size_t hypot_cnt;
2969 size_t hypot_cap;
2970 /* Whether hypothetical mapping, if successful, would need to adjust
2971 * already canonicalized types (due to a new forward declaration to
2972 * concrete type resolution). In such case, during split BTF dedup
2973 * candidate type would still be considered as different, because base
2974 * BTF is considered to be immutable.
2975 */
2976 bool hypot_adjust_canon;
2977 /* Various option modifying behavior of algorithm */
2978 struct btf_dedup_opts opts;
2979 /* temporary strings deduplication state */
2980 struct strset *strs_set;
2981 };
2982
hash_combine(long h,long value)2983 static long hash_combine(long h, long value)
2984 {
2985 return h * 31 + value;
2986 }
2987
2988 #define for_each_dedup_cand(d, node, hash) \
2989 hashmap__for_each_key_entry(d->dedup_table, node, (void *)hash)
2990
btf_dedup_table_add(struct btf_dedup * d,long hash,__u32 type_id)2991 static int btf_dedup_table_add(struct btf_dedup *d, long hash, __u32 type_id)
2992 {
2993 return hashmap__append(d->dedup_table,
2994 (void *)hash, (void *)(long)type_id);
2995 }
2996
btf_dedup_hypot_map_add(struct btf_dedup * d,__u32 from_id,__u32 to_id)2997 static int btf_dedup_hypot_map_add(struct btf_dedup *d,
2998 __u32 from_id, __u32 to_id)
2999 {
3000 if (d->hypot_cnt == d->hypot_cap) {
3001 __u32 *new_list;
3002
3003 d->hypot_cap += max((size_t)16, d->hypot_cap / 2);
3004 new_list = libbpf_reallocarray(d->hypot_list, d->hypot_cap, sizeof(__u32));
3005 if (!new_list)
3006 return -ENOMEM;
3007 d->hypot_list = new_list;
3008 }
3009 d->hypot_list[d->hypot_cnt++] = from_id;
3010 d->hypot_map[from_id] = to_id;
3011 return 0;
3012 }
3013
btf_dedup_clear_hypot_map(struct btf_dedup * d)3014 static void btf_dedup_clear_hypot_map(struct btf_dedup *d)
3015 {
3016 int i;
3017
3018 for (i = 0; i < d->hypot_cnt; i++)
3019 d->hypot_map[d->hypot_list[i]] = BTF_UNPROCESSED_ID;
3020 d->hypot_cnt = 0;
3021 d->hypot_adjust_canon = false;
3022 }
3023
btf_dedup_free(struct btf_dedup * d)3024 static void btf_dedup_free(struct btf_dedup *d)
3025 {
3026 hashmap__free(d->dedup_table);
3027 d->dedup_table = NULL;
3028
3029 free(d->map);
3030 d->map = NULL;
3031
3032 free(d->hypot_map);
3033 d->hypot_map = NULL;
3034
3035 free(d->hypot_list);
3036 d->hypot_list = NULL;
3037
3038 free(d);
3039 }
3040
btf_dedup_identity_hash_fn(const void * key,void * ctx)3041 static size_t btf_dedup_identity_hash_fn(const void *key, void *ctx)
3042 {
3043 return (size_t)key;
3044 }
3045
btf_dedup_collision_hash_fn(const void * key,void * ctx)3046 static size_t btf_dedup_collision_hash_fn(const void *key, void *ctx)
3047 {
3048 return 0;
3049 }
3050
btf_dedup_equal_fn(const void * k1,const void * k2,void * ctx)3051 static bool btf_dedup_equal_fn(const void *k1, const void *k2, void *ctx)
3052 {
3053 return k1 == k2;
3054 }
3055
btf_dedup_new(struct btf * btf,struct btf_ext * btf_ext,const struct btf_dedup_opts * opts)3056 static struct btf_dedup *btf_dedup_new(struct btf *btf, struct btf_ext *btf_ext,
3057 const struct btf_dedup_opts *opts)
3058 {
3059 struct btf_dedup *d = calloc(1, sizeof(struct btf_dedup));
3060 hashmap_hash_fn hash_fn = btf_dedup_identity_hash_fn;
3061 int i, err = 0, type_cnt;
3062
3063 if (!d)
3064 return ERR_PTR(-ENOMEM);
3065
3066 d->opts.dont_resolve_fwds = opts && opts->dont_resolve_fwds;
3067 /* dedup_table_size is now used only to force collisions in tests */
3068 if (opts && opts->dedup_table_size == 1)
3069 hash_fn = btf_dedup_collision_hash_fn;
3070
3071 d->btf = btf;
3072 d->btf_ext = btf_ext;
3073
3074 d->dedup_table = hashmap__new(hash_fn, btf_dedup_equal_fn, NULL);
3075 if (IS_ERR(d->dedup_table)) {
3076 err = PTR_ERR(d->dedup_table);
3077 d->dedup_table = NULL;
3078 goto done;
3079 }
3080
3081 type_cnt = btf__get_nr_types(btf) + 1;
3082 d->map = malloc(sizeof(__u32) * type_cnt);
3083 if (!d->map) {
3084 err = -ENOMEM;
3085 goto done;
3086 }
3087 /* special BTF "void" type is made canonical immediately */
3088 d->map[0] = 0;
3089 for (i = 1; i < type_cnt; i++) {
3090 struct btf_type *t = btf_type_by_id(d->btf, i);
3091
3092 /* VAR and DATASEC are never deduped and are self-canonical */
3093 if (btf_is_var(t) || btf_is_datasec(t))
3094 d->map[i] = i;
3095 else
3096 d->map[i] = BTF_UNPROCESSED_ID;
3097 }
3098
3099 d->hypot_map = malloc(sizeof(__u32) * type_cnt);
3100 if (!d->hypot_map) {
3101 err = -ENOMEM;
3102 goto done;
3103 }
3104 for (i = 0; i < type_cnt; i++)
3105 d->hypot_map[i] = BTF_UNPROCESSED_ID;
3106
3107 done:
3108 if (err) {
3109 btf_dedup_free(d);
3110 return ERR_PTR(err);
3111 }
3112
3113 return d;
3114 }
3115
3116 /*
3117 * Iterate over all possible places in .BTF and .BTF.ext that can reference
3118 * string and pass pointer to it to a provided callback `fn`.
3119 */
btf_for_each_str_off(struct btf_dedup * d,str_off_visit_fn fn,void * ctx)3120 static int btf_for_each_str_off(struct btf_dedup *d, str_off_visit_fn fn, void *ctx)
3121 {
3122 int i, r;
3123
3124 for (i = 0; i < d->btf->nr_types; i++) {
3125 struct btf_type *t = btf_type_by_id(d->btf, d->btf->start_id + i);
3126
3127 r = btf_type_visit_str_offs(t, fn, ctx);
3128 if (r)
3129 return r;
3130 }
3131
3132 if (!d->btf_ext)
3133 return 0;
3134
3135 r = btf_ext_visit_str_offs(d->btf_ext, fn, ctx);
3136 if (r)
3137 return r;
3138
3139 return 0;
3140 }
3141
strs_dedup_remap_str_off(__u32 * str_off_ptr,void * ctx)3142 static int strs_dedup_remap_str_off(__u32 *str_off_ptr, void *ctx)
3143 {
3144 struct btf_dedup *d = ctx;
3145 __u32 str_off = *str_off_ptr;
3146 const char *s;
3147 int off, err;
3148
3149 /* don't touch empty string or string in main BTF */
3150 if (str_off == 0 || str_off < d->btf->start_str_off)
3151 return 0;
3152
3153 s = btf__str_by_offset(d->btf, str_off);
3154 if (d->btf->base_btf) {
3155 err = btf__find_str(d->btf->base_btf, s);
3156 if (err >= 0) {
3157 *str_off_ptr = err;
3158 return 0;
3159 }
3160 if (err != -ENOENT)
3161 return err;
3162 }
3163
3164 off = strset__add_str(d->strs_set, s);
3165 if (off < 0)
3166 return off;
3167
3168 *str_off_ptr = d->btf->start_str_off + off;
3169 return 0;
3170 }
3171
3172 /*
3173 * Dedup string and filter out those that are not referenced from either .BTF
3174 * or .BTF.ext (if provided) sections.
3175 *
3176 * This is done by building index of all strings in BTF's string section,
3177 * then iterating over all entities that can reference strings (e.g., type
3178 * names, struct field names, .BTF.ext line info, etc) and marking corresponding
3179 * strings as used. After that all used strings are deduped and compacted into
3180 * sequential blob of memory and new offsets are calculated. Then all the string
3181 * references are iterated again and rewritten using new offsets.
3182 */
btf_dedup_strings(struct btf_dedup * d)3183 static int btf_dedup_strings(struct btf_dedup *d)
3184 {
3185 int err;
3186
3187 if (d->btf->strs_deduped)
3188 return 0;
3189
3190 d->strs_set = strset__new(BTF_MAX_STR_OFFSET, NULL, 0);
3191 if (IS_ERR(d->strs_set)) {
3192 err = PTR_ERR(d->strs_set);
3193 goto err_out;
3194 }
3195
3196 if (!d->btf->base_btf) {
3197 /* insert empty string; we won't be looking it up during strings
3198 * dedup, but it's good to have it for generic BTF string lookups
3199 */
3200 err = strset__add_str(d->strs_set, "");
3201 if (err < 0)
3202 goto err_out;
3203 }
3204
3205 /* remap string offsets */
3206 err = btf_for_each_str_off(d, strs_dedup_remap_str_off, d);
3207 if (err)
3208 goto err_out;
3209
3210 /* replace BTF string data and hash with deduped ones */
3211 strset__free(d->btf->strs_set);
3212 d->btf->hdr->str_len = strset__data_size(d->strs_set);
3213 d->btf->strs_set = d->strs_set;
3214 d->strs_set = NULL;
3215 d->btf->strs_deduped = true;
3216 return 0;
3217
3218 err_out:
3219 strset__free(d->strs_set);
3220 d->strs_set = NULL;
3221
3222 return err;
3223 }
3224
btf_hash_common(struct btf_type * t)3225 static long btf_hash_common(struct btf_type *t)
3226 {
3227 long h;
3228
3229 h = hash_combine(0, t->name_off);
3230 h = hash_combine(h, t->info);
3231 h = hash_combine(h, t->size);
3232 return h;
3233 }
3234
btf_equal_common(struct btf_type * t1,struct btf_type * t2)3235 static bool btf_equal_common(struct btf_type *t1, struct btf_type *t2)
3236 {
3237 return t1->name_off == t2->name_off &&
3238 t1->info == t2->info &&
3239 t1->size == t2->size;
3240 }
3241
3242 /* Calculate type signature hash of INT. */
btf_hash_int(struct btf_type * t)3243 static long btf_hash_int(struct btf_type *t)
3244 {
3245 __u32 info = *(__u32 *)(t + 1);
3246 long h;
3247
3248 h = btf_hash_common(t);
3249 h = hash_combine(h, info);
3250 return h;
3251 }
3252
3253 /* Check structural equality of two INTs. */
btf_equal_int(struct btf_type * t1,struct btf_type * t2)3254 static bool btf_equal_int(struct btf_type *t1, struct btf_type *t2)
3255 {
3256 __u32 info1, info2;
3257
3258 if (!btf_equal_common(t1, t2))
3259 return false;
3260 info1 = *(__u32 *)(t1 + 1);
3261 info2 = *(__u32 *)(t2 + 1);
3262 return info1 == info2;
3263 }
3264
3265 /* Calculate type signature hash of ENUM. */
btf_hash_enum(struct btf_type * t)3266 static long btf_hash_enum(struct btf_type *t)
3267 {
3268 long h;
3269
3270 /* don't hash vlen and enum members to support enum fwd resolving */
3271 h = hash_combine(0, t->name_off);
3272 h = hash_combine(h, t->info & ~0xffff);
3273 h = hash_combine(h, t->size);
3274 return h;
3275 }
3276
3277 /* Check structural equality of two ENUMs. */
btf_equal_enum(struct btf_type * t1,struct btf_type * t2)3278 static bool btf_equal_enum(struct btf_type *t1, struct btf_type *t2)
3279 {
3280 const struct btf_enum *m1, *m2;
3281 __u16 vlen;
3282 int i;
3283
3284 if (!btf_equal_common(t1, t2))
3285 return false;
3286
3287 vlen = btf_vlen(t1);
3288 m1 = btf_enum(t1);
3289 m2 = btf_enum(t2);
3290 for (i = 0; i < vlen; i++) {
3291 if (m1->name_off != m2->name_off || m1->val != m2->val)
3292 return false;
3293 m1++;
3294 m2++;
3295 }
3296 return true;
3297 }
3298
btf_is_enum_fwd(struct btf_type * t)3299 static inline bool btf_is_enum_fwd(struct btf_type *t)
3300 {
3301 return btf_is_enum(t) && btf_vlen(t) == 0;
3302 }
3303
btf_compat_enum(struct btf_type * t1,struct btf_type * t2)3304 static bool btf_compat_enum(struct btf_type *t1, struct btf_type *t2)
3305 {
3306 if (!btf_is_enum_fwd(t1) && !btf_is_enum_fwd(t2))
3307 return btf_equal_enum(t1, t2);
3308 /* ignore vlen when comparing */
3309 return t1->name_off == t2->name_off &&
3310 (t1->info & ~0xffff) == (t2->info & ~0xffff) &&
3311 t1->size == t2->size;
3312 }
3313
3314 /*
3315 * Calculate type signature hash of STRUCT/UNION, ignoring referenced type IDs,
3316 * as referenced type IDs equivalence is established separately during type
3317 * graph equivalence check algorithm.
3318 */
btf_hash_struct(struct btf_type * t)3319 static long btf_hash_struct(struct btf_type *t)
3320 {
3321 const struct btf_member *member = btf_members(t);
3322 __u32 vlen = btf_vlen(t);
3323 long h = btf_hash_common(t);
3324 int i;
3325
3326 for (i = 0; i < vlen; i++) {
3327 h = hash_combine(h, member->name_off);
3328 h = hash_combine(h, member->offset);
3329 /* no hashing of referenced type ID, it can be unresolved yet */
3330 member++;
3331 }
3332 return h;
3333 }
3334
3335 /*
3336 * Check structural compatibility of two FUNC_PROTOs, ignoring referenced type
3337 * IDs. This check is performed during type graph equivalence check and
3338 * referenced types equivalence is checked separately.
3339 */
btf_shallow_equal_struct(struct btf_type * t1,struct btf_type * t2)3340 static bool btf_shallow_equal_struct(struct btf_type *t1, struct btf_type *t2)
3341 {
3342 const struct btf_member *m1, *m2;
3343 __u16 vlen;
3344 int i;
3345
3346 if (!btf_equal_common(t1, t2))
3347 return false;
3348
3349 vlen = btf_vlen(t1);
3350 m1 = btf_members(t1);
3351 m2 = btf_members(t2);
3352 for (i = 0; i < vlen; i++) {
3353 if (m1->name_off != m2->name_off || m1->offset != m2->offset)
3354 return false;
3355 m1++;
3356 m2++;
3357 }
3358 return true;
3359 }
3360
3361 /*
3362 * Calculate type signature hash of ARRAY, including referenced type IDs,
3363 * under assumption that they were already resolved to canonical type IDs and
3364 * are not going to change.
3365 */
btf_hash_array(struct btf_type * t)3366 static long btf_hash_array(struct btf_type *t)
3367 {
3368 const struct btf_array *info = btf_array(t);
3369 long h = btf_hash_common(t);
3370
3371 h = hash_combine(h, info->type);
3372 h = hash_combine(h, info->index_type);
3373 h = hash_combine(h, info->nelems);
3374 return h;
3375 }
3376
3377 /*
3378 * Check exact equality of two ARRAYs, taking into account referenced
3379 * type IDs, under assumption that they were already resolved to canonical
3380 * type IDs and are not going to change.
3381 * This function is called during reference types deduplication to compare
3382 * ARRAY to potential canonical representative.
3383 */
btf_equal_array(struct btf_type * t1,struct btf_type * t2)3384 static bool btf_equal_array(struct btf_type *t1, struct btf_type *t2)
3385 {
3386 const struct btf_array *info1, *info2;
3387
3388 if (!btf_equal_common(t1, t2))
3389 return false;
3390
3391 info1 = btf_array(t1);
3392 info2 = btf_array(t2);
3393 return info1->type == info2->type &&
3394 info1->index_type == info2->index_type &&
3395 info1->nelems == info2->nelems;
3396 }
3397
3398 /*
3399 * Check structural compatibility of two ARRAYs, ignoring referenced type
3400 * IDs. This check is performed during type graph equivalence check and
3401 * referenced types equivalence is checked separately.
3402 */
btf_compat_array(struct btf_type * t1,struct btf_type * t2)3403 static bool btf_compat_array(struct btf_type *t1, struct btf_type *t2)
3404 {
3405 if (!btf_equal_common(t1, t2))
3406 return false;
3407
3408 return btf_array(t1)->nelems == btf_array(t2)->nelems;
3409 }
3410
3411 /*
3412 * Calculate type signature hash of FUNC_PROTO, including referenced type IDs,
3413 * under assumption that they were already resolved to canonical type IDs and
3414 * are not going to change.
3415 */
btf_hash_fnproto(struct btf_type * t)3416 static long btf_hash_fnproto(struct btf_type *t)
3417 {
3418 const struct btf_param *member = btf_params(t);
3419 __u16 vlen = btf_vlen(t);
3420 long h = btf_hash_common(t);
3421 int i;
3422
3423 for (i = 0; i < vlen; i++) {
3424 h = hash_combine(h, member->name_off);
3425 h = hash_combine(h, member->type);
3426 member++;
3427 }
3428 return h;
3429 }
3430
3431 /*
3432 * Check exact equality of two FUNC_PROTOs, taking into account referenced
3433 * type IDs, under assumption that they were already resolved to canonical
3434 * type IDs and are not going to change.
3435 * This function is called during reference types deduplication to compare
3436 * FUNC_PROTO to potential canonical representative.
3437 */
btf_equal_fnproto(struct btf_type * t1,struct btf_type * t2)3438 static bool btf_equal_fnproto(struct btf_type *t1, struct btf_type *t2)
3439 {
3440 const struct btf_param *m1, *m2;
3441 __u16 vlen;
3442 int i;
3443
3444 if (!btf_equal_common(t1, t2))
3445 return false;
3446
3447 vlen = btf_vlen(t1);
3448 m1 = btf_params(t1);
3449 m2 = btf_params(t2);
3450 for (i = 0; i < vlen; i++) {
3451 if (m1->name_off != m2->name_off || m1->type != m2->type)
3452 return false;
3453 m1++;
3454 m2++;
3455 }
3456 return true;
3457 }
3458
3459 /*
3460 * Check structural compatibility of two FUNC_PROTOs, ignoring referenced type
3461 * IDs. This check is performed during type graph equivalence check and
3462 * referenced types equivalence is checked separately.
3463 */
btf_compat_fnproto(struct btf_type * t1,struct btf_type * t2)3464 static bool btf_compat_fnproto(struct btf_type *t1, struct btf_type *t2)
3465 {
3466 const struct btf_param *m1, *m2;
3467 __u16 vlen;
3468 int i;
3469
3470 /* skip return type ID */
3471 if (t1->name_off != t2->name_off || t1->info != t2->info)
3472 return false;
3473
3474 vlen = btf_vlen(t1);
3475 m1 = btf_params(t1);
3476 m2 = btf_params(t2);
3477 for (i = 0; i < vlen; i++) {
3478 if (m1->name_off != m2->name_off)
3479 return false;
3480 m1++;
3481 m2++;
3482 }
3483 return true;
3484 }
3485
3486 /* Prepare split BTF for deduplication by calculating hashes of base BTF's
3487 * types and initializing the rest of the state (canonical type mapping) for
3488 * the fixed base BTF part.
3489 */
btf_dedup_prep(struct btf_dedup * d)3490 static int btf_dedup_prep(struct btf_dedup *d)
3491 {
3492 struct btf_type *t;
3493 int type_id;
3494 long h;
3495
3496 if (!d->btf->base_btf)
3497 return 0;
3498
3499 for (type_id = 1; type_id < d->btf->start_id; type_id++) {
3500 t = btf_type_by_id(d->btf, type_id);
3501
3502 /* all base BTF types are self-canonical by definition */
3503 d->map[type_id] = type_id;
3504
3505 switch (btf_kind(t)) {
3506 case BTF_KIND_VAR:
3507 case BTF_KIND_DATASEC:
3508 /* VAR and DATASEC are never hash/deduplicated */
3509 continue;
3510 case BTF_KIND_CONST:
3511 case BTF_KIND_VOLATILE:
3512 case BTF_KIND_RESTRICT:
3513 case BTF_KIND_PTR:
3514 case BTF_KIND_FWD:
3515 case BTF_KIND_TYPEDEF:
3516 case BTF_KIND_FUNC:
3517 case BTF_KIND_FLOAT:
3518 h = btf_hash_common(t);
3519 break;
3520 case BTF_KIND_INT:
3521 h = btf_hash_int(t);
3522 break;
3523 case BTF_KIND_ENUM:
3524 h = btf_hash_enum(t);
3525 break;
3526 case BTF_KIND_STRUCT:
3527 case BTF_KIND_UNION:
3528 h = btf_hash_struct(t);
3529 break;
3530 case BTF_KIND_ARRAY:
3531 h = btf_hash_array(t);
3532 break;
3533 case BTF_KIND_FUNC_PROTO:
3534 h = btf_hash_fnproto(t);
3535 break;
3536 default:
3537 pr_debug("unknown kind %d for type [%d]\n", btf_kind(t), type_id);
3538 return -EINVAL;
3539 }
3540 if (btf_dedup_table_add(d, h, type_id))
3541 return -ENOMEM;
3542 }
3543
3544 return 0;
3545 }
3546
3547 /*
3548 * Deduplicate primitive types, that can't reference other types, by calculating
3549 * their type signature hash and comparing them with any possible canonical
3550 * candidate. If no canonical candidate matches, type itself is marked as
3551 * canonical and is added into `btf_dedup->dedup_table` as another candidate.
3552 */
btf_dedup_prim_type(struct btf_dedup * d,__u32 type_id)3553 static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_id)
3554 {
3555 struct btf_type *t = btf_type_by_id(d->btf, type_id);
3556 struct hashmap_entry *hash_entry;
3557 struct btf_type *cand;
3558 /* if we don't find equivalent type, then we are canonical */
3559 __u32 new_id = type_id;
3560 __u32 cand_id;
3561 long h;
3562
3563 switch (btf_kind(t)) {
3564 case BTF_KIND_CONST:
3565 case BTF_KIND_VOLATILE:
3566 case BTF_KIND_RESTRICT:
3567 case BTF_KIND_PTR:
3568 case BTF_KIND_TYPEDEF:
3569 case BTF_KIND_ARRAY:
3570 case BTF_KIND_STRUCT:
3571 case BTF_KIND_UNION:
3572 case BTF_KIND_FUNC:
3573 case BTF_KIND_FUNC_PROTO:
3574 case BTF_KIND_VAR:
3575 case BTF_KIND_DATASEC:
3576 return 0;
3577
3578 case BTF_KIND_INT:
3579 h = btf_hash_int(t);
3580 for_each_dedup_cand(d, hash_entry, h) {
3581 cand_id = (__u32)(long)hash_entry->value;
3582 cand = btf_type_by_id(d->btf, cand_id);
3583 if (btf_equal_int(t, cand)) {
3584 new_id = cand_id;
3585 break;
3586 }
3587 }
3588 break;
3589
3590 case BTF_KIND_ENUM:
3591 h = btf_hash_enum(t);
3592 for_each_dedup_cand(d, hash_entry, h) {
3593 cand_id = (__u32)(long)hash_entry->value;
3594 cand = btf_type_by_id(d->btf, cand_id);
3595 if (btf_equal_enum(t, cand)) {
3596 new_id = cand_id;
3597 break;
3598 }
3599 if (d->opts.dont_resolve_fwds)
3600 continue;
3601 if (btf_compat_enum(t, cand)) {
3602 if (btf_is_enum_fwd(t)) {
3603 /* resolve fwd to full enum */
3604 new_id = cand_id;
3605 break;
3606 }
3607 /* resolve canonical enum fwd to full enum */
3608 d->map[cand_id] = type_id;
3609 }
3610 }
3611 break;
3612
3613 case BTF_KIND_FWD:
3614 case BTF_KIND_FLOAT:
3615 h = btf_hash_common(t);
3616 for_each_dedup_cand(d, hash_entry, h) {
3617 cand_id = (__u32)(long)hash_entry->value;
3618 cand = btf_type_by_id(d->btf, cand_id);
3619 if (btf_equal_common(t, cand)) {
3620 new_id = cand_id;
3621 break;
3622 }
3623 }
3624 break;
3625
3626 default:
3627 return -EINVAL;
3628 }
3629
3630 d->map[type_id] = new_id;
3631 if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
3632 return -ENOMEM;
3633
3634 return 0;
3635 }
3636
btf_dedup_prim_types(struct btf_dedup * d)3637 static int btf_dedup_prim_types(struct btf_dedup *d)
3638 {
3639 int i, err;
3640
3641 for (i = 0; i < d->btf->nr_types; i++) {
3642 err = btf_dedup_prim_type(d, d->btf->start_id + i);
3643 if (err)
3644 return err;
3645 }
3646 return 0;
3647 }
3648
3649 /*
3650 * Check whether type is already mapped into canonical one (could be to itself).
3651 */
is_type_mapped(struct btf_dedup * d,uint32_t type_id)3652 static inline bool is_type_mapped(struct btf_dedup *d, uint32_t type_id)
3653 {
3654 return d->map[type_id] <= BTF_MAX_NR_TYPES;
3655 }
3656
3657 /*
3658 * Resolve type ID into its canonical type ID, if any; otherwise return original
3659 * type ID. If type is FWD and is resolved into STRUCT/UNION already, follow
3660 * STRUCT/UNION link and resolve it into canonical type ID as well.
3661 */
resolve_type_id(struct btf_dedup * d,__u32 type_id)3662 static inline __u32 resolve_type_id(struct btf_dedup *d, __u32 type_id)
3663 {
3664 while (is_type_mapped(d, type_id) && d->map[type_id] != type_id)
3665 type_id = d->map[type_id];
3666 return type_id;
3667 }
3668
3669 /*
3670 * Resolve FWD to underlying STRUCT/UNION, if any; otherwise return original
3671 * type ID.
3672 */
resolve_fwd_id(struct btf_dedup * d,uint32_t type_id)3673 static uint32_t resolve_fwd_id(struct btf_dedup *d, uint32_t type_id)
3674 {
3675 __u32 orig_type_id = type_id;
3676
3677 if (!btf_is_fwd(btf__type_by_id(d->btf, type_id)))
3678 return type_id;
3679
3680 while (is_type_mapped(d, type_id) && d->map[type_id] != type_id)
3681 type_id = d->map[type_id];
3682
3683 if (!btf_is_fwd(btf__type_by_id(d->btf, type_id)))
3684 return type_id;
3685
3686 return orig_type_id;
3687 }
3688
3689
btf_fwd_kind(struct btf_type * t)3690 static inline __u16 btf_fwd_kind(struct btf_type *t)
3691 {
3692 return btf_kflag(t) ? BTF_KIND_UNION : BTF_KIND_STRUCT;
3693 }
3694
3695 /* Check if given two types are identical ARRAY definitions */
btf_dedup_identical_arrays(struct btf_dedup * d,__u32 id1,__u32 id2)3696 static int btf_dedup_identical_arrays(struct btf_dedup *d, __u32 id1, __u32 id2)
3697 {
3698 struct btf_type *t1, *t2;
3699
3700 t1 = btf_type_by_id(d->btf, id1);
3701 t2 = btf_type_by_id(d->btf, id2);
3702 if (!btf_is_array(t1) || !btf_is_array(t2))
3703 return 0;
3704
3705 return btf_equal_array(t1, t2);
3706 }
3707
3708 /*
3709 * Check equivalence of BTF type graph formed by candidate struct/union (we'll
3710 * call it "candidate graph" in this description for brevity) to a type graph
3711 * formed by (potential) canonical struct/union ("canonical graph" for brevity
3712 * here, though keep in mind that not all types in canonical graph are
3713 * necessarily canonical representatives themselves, some of them might be
3714 * duplicates or its uniqueness might not have been established yet).
3715 * Returns:
3716 * - >0, if type graphs are equivalent;
3717 * - 0, if not equivalent;
3718 * - <0, on error.
3719 *
3720 * Algorithm performs side-by-side DFS traversal of both type graphs and checks
3721 * equivalence of BTF types at each step. If at any point BTF types in candidate
3722 * and canonical graphs are not compatible structurally, whole graphs are
3723 * incompatible. If types are structurally equivalent (i.e., all information
3724 * except referenced type IDs is exactly the same), a mapping from `canon_id` to
3725 * a `cand_id` is recored in hypothetical mapping (`btf_dedup->hypot_map`).
3726 * If a type references other types, then those referenced types are checked
3727 * for equivalence recursively.
3728 *
3729 * During DFS traversal, if we find that for current `canon_id` type we
3730 * already have some mapping in hypothetical map, we check for two possible
3731 * situations:
3732 * - `canon_id` is mapped to exactly the same type as `cand_id`. This will
3733 * happen when type graphs have cycles. In this case we assume those two
3734 * types are equivalent.
3735 * - `canon_id` is mapped to different type. This is contradiction in our
3736 * hypothetical mapping, because same graph in canonical graph corresponds
3737 * to two different types in candidate graph, which for equivalent type
3738 * graphs shouldn't happen. This condition terminates equivalence check
3739 * with negative result.
3740 *
3741 * If type graphs traversal exhausts types to check and find no contradiction,
3742 * then type graphs are equivalent.
3743 *
3744 * When checking types for equivalence, there is one special case: FWD types.
3745 * If FWD type resolution is allowed and one of the types (either from canonical
3746 * or candidate graph) is FWD and other is STRUCT/UNION (depending on FWD's kind
3747 * flag) and their names match, hypothetical mapping is updated to point from
3748 * FWD to STRUCT/UNION. If graphs will be determined as equivalent successfully,
3749 * this mapping will be used to record FWD -> STRUCT/UNION mapping permanently.
3750 *
3751 * Technically, this could lead to incorrect FWD to STRUCT/UNION resolution,
3752 * if there are two exactly named (or anonymous) structs/unions that are
3753 * compatible structurally, one of which has FWD field, while other is concrete
3754 * STRUCT/UNION, but according to C sources they are different structs/unions
3755 * that are referencing different types with the same name. This is extremely
3756 * unlikely to happen, but btf_dedup API allows to disable FWD resolution if
3757 * this logic is causing problems.
3758 *
3759 * Doing FWD resolution means that both candidate and/or canonical graphs can
3760 * consists of portions of the graph that come from multiple compilation units.
3761 * This is due to the fact that types within single compilation unit are always
3762 * deduplicated and FWDs are already resolved, if referenced struct/union
3763 * definiton is available. So, if we had unresolved FWD and found corresponding
3764 * STRUCT/UNION, they will be from different compilation units. This
3765 * consequently means that when we "link" FWD to corresponding STRUCT/UNION,
3766 * type graph will likely have at least two different BTF types that describe
3767 * same type (e.g., most probably there will be two different BTF types for the
3768 * same 'int' primitive type) and could even have "overlapping" parts of type
3769 * graph that describe same subset of types.
3770 *
3771 * This in turn means that our assumption that each type in canonical graph
3772 * must correspond to exactly one type in candidate graph might not hold
3773 * anymore and will make it harder to detect contradictions using hypothetical
3774 * map. To handle this problem, we allow to follow FWD -> STRUCT/UNION
3775 * resolution only in canonical graph. FWDs in candidate graphs are never
3776 * resolved. To see why it's OK, let's check all possible situations w.r.t. FWDs
3777 * that can occur:
3778 * - Both types in canonical and candidate graphs are FWDs. If they are
3779 * structurally equivalent, then they can either be both resolved to the
3780 * same STRUCT/UNION or not resolved at all. In both cases they are
3781 * equivalent and there is no need to resolve FWD on candidate side.
3782 * - Both types in canonical and candidate graphs are concrete STRUCT/UNION,
3783 * so nothing to resolve as well, algorithm will check equivalence anyway.
3784 * - Type in canonical graph is FWD, while type in candidate is concrete
3785 * STRUCT/UNION. In this case candidate graph comes from single compilation
3786 * unit, so there is exactly one BTF type for each unique C type. After
3787 * resolving FWD into STRUCT/UNION, there might be more than one BTF type
3788 * in canonical graph mapping to single BTF type in candidate graph, but
3789 * because hypothetical mapping maps from canonical to candidate types, it's
3790 * alright, and we still maintain the property of having single `canon_id`
3791 * mapping to single `cand_id` (there could be two different `canon_id`
3792 * mapped to the same `cand_id`, but it's not contradictory).
3793 * - Type in canonical graph is concrete STRUCT/UNION, while type in candidate
3794 * graph is FWD. In this case we are just going to check compatibility of
3795 * STRUCT/UNION and corresponding FWD, and if they are compatible, we'll
3796 * assume that whatever STRUCT/UNION FWD resolves to must be equivalent to
3797 * a concrete STRUCT/UNION from canonical graph. If the rest of type graphs
3798 * turn out equivalent, we'll re-resolve FWD to concrete STRUCT/UNION from
3799 * canonical graph.
3800 */
btf_dedup_is_equiv(struct btf_dedup * d,__u32 cand_id,__u32 canon_id)3801 static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,
3802 __u32 canon_id)
3803 {
3804 struct btf_type *cand_type;
3805 struct btf_type *canon_type;
3806 __u32 hypot_type_id;
3807 __u16 cand_kind;
3808 __u16 canon_kind;
3809 int i, eq;
3810
3811 /* if both resolve to the same canonical, they must be equivalent */
3812 if (resolve_type_id(d, cand_id) == resolve_type_id(d, canon_id))
3813 return 1;
3814
3815 canon_id = resolve_fwd_id(d, canon_id);
3816
3817 hypot_type_id = d->hypot_map[canon_id];
3818 if (hypot_type_id <= BTF_MAX_NR_TYPES) {
3819 /* In some cases compiler will generate different DWARF types
3820 * for *identical* array type definitions and use them for
3821 * different fields within the *same* struct. This breaks type
3822 * equivalence check, which makes an assumption that candidate
3823 * types sub-graph has a consistent and deduped-by-compiler
3824 * types within a single CU. So work around that by explicitly
3825 * allowing identical array types here.
3826 */
3827 return hypot_type_id == cand_id ||
3828 btf_dedup_identical_arrays(d, hypot_type_id, cand_id);
3829 }
3830
3831 if (btf_dedup_hypot_map_add(d, canon_id, cand_id))
3832 return -ENOMEM;
3833
3834 cand_type = btf_type_by_id(d->btf, cand_id);
3835 canon_type = btf_type_by_id(d->btf, canon_id);
3836 cand_kind = btf_kind(cand_type);
3837 canon_kind = btf_kind(canon_type);
3838
3839 if (cand_type->name_off != canon_type->name_off)
3840 return 0;
3841
3842 /* FWD <--> STRUCT/UNION equivalence check, if enabled */
3843 if (!d->opts.dont_resolve_fwds
3844 && (cand_kind == BTF_KIND_FWD || canon_kind == BTF_KIND_FWD)
3845 && cand_kind != canon_kind) {
3846 __u16 real_kind;
3847 __u16 fwd_kind;
3848
3849 if (cand_kind == BTF_KIND_FWD) {
3850 real_kind = canon_kind;
3851 fwd_kind = btf_fwd_kind(cand_type);
3852 } else {
3853 real_kind = cand_kind;
3854 fwd_kind = btf_fwd_kind(canon_type);
3855 /* we'd need to resolve base FWD to STRUCT/UNION */
3856 if (fwd_kind == real_kind && canon_id < d->btf->start_id)
3857 d->hypot_adjust_canon = true;
3858 }
3859 return fwd_kind == real_kind;
3860 }
3861
3862 if (cand_kind != canon_kind)
3863 return 0;
3864
3865 switch (cand_kind) {
3866 case BTF_KIND_INT:
3867 return btf_equal_int(cand_type, canon_type);
3868
3869 case BTF_KIND_ENUM:
3870 if (d->opts.dont_resolve_fwds)
3871 return btf_equal_enum(cand_type, canon_type);
3872 else
3873 return btf_compat_enum(cand_type, canon_type);
3874
3875 case BTF_KIND_FWD:
3876 case BTF_KIND_FLOAT:
3877 return btf_equal_common(cand_type, canon_type);
3878
3879 case BTF_KIND_CONST:
3880 case BTF_KIND_VOLATILE:
3881 case BTF_KIND_RESTRICT:
3882 case BTF_KIND_PTR:
3883 case BTF_KIND_TYPEDEF:
3884 case BTF_KIND_FUNC:
3885 if (cand_type->info != canon_type->info)
3886 return 0;
3887 return btf_dedup_is_equiv(d, cand_type->type, canon_type->type);
3888
3889 case BTF_KIND_ARRAY: {
3890 const struct btf_array *cand_arr, *canon_arr;
3891
3892 if (!btf_compat_array(cand_type, canon_type))
3893 return 0;
3894 cand_arr = btf_array(cand_type);
3895 canon_arr = btf_array(canon_type);
3896 eq = btf_dedup_is_equiv(d, cand_arr->index_type, canon_arr->index_type);
3897 if (eq <= 0)
3898 return eq;
3899 return btf_dedup_is_equiv(d, cand_arr->type, canon_arr->type);
3900 }
3901
3902 case BTF_KIND_STRUCT:
3903 case BTF_KIND_UNION: {
3904 const struct btf_member *cand_m, *canon_m;
3905 __u16 vlen;
3906
3907 if (!btf_shallow_equal_struct(cand_type, canon_type))
3908 return 0;
3909 vlen = btf_vlen(cand_type);
3910 cand_m = btf_members(cand_type);
3911 canon_m = btf_members(canon_type);
3912 for (i = 0; i < vlen; i++) {
3913 eq = btf_dedup_is_equiv(d, cand_m->type, canon_m->type);
3914 if (eq <= 0)
3915 return eq;
3916 cand_m++;
3917 canon_m++;
3918 }
3919
3920 return 1;
3921 }
3922
3923 case BTF_KIND_FUNC_PROTO: {
3924 const struct btf_param *cand_p, *canon_p;
3925 __u16 vlen;
3926
3927 if (!btf_compat_fnproto(cand_type, canon_type))
3928 return 0;
3929 eq = btf_dedup_is_equiv(d, cand_type->type, canon_type->type);
3930 if (eq <= 0)
3931 return eq;
3932 vlen = btf_vlen(cand_type);
3933 cand_p = btf_params(cand_type);
3934 canon_p = btf_params(canon_type);
3935 for (i = 0; i < vlen; i++) {
3936 eq = btf_dedup_is_equiv(d, cand_p->type, canon_p->type);
3937 if (eq <= 0)
3938 return eq;
3939 cand_p++;
3940 canon_p++;
3941 }
3942 return 1;
3943 }
3944
3945 default:
3946 return -EINVAL;
3947 }
3948 return 0;
3949 }
3950
3951 /*
3952 * Use hypothetical mapping, produced by successful type graph equivalence
3953 * check, to augment existing struct/union canonical mapping, where possible.
3954 *
3955 * If BTF_KIND_FWD resolution is allowed, this mapping is also used to record
3956 * FWD -> STRUCT/UNION correspondence as well. FWD resolution is bidirectional:
3957 * it doesn't matter if FWD type was part of canonical graph or candidate one,
3958 * we are recording the mapping anyway. As opposed to carefulness required
3959 * for struct/union correspondence mapping (described below), for FWD resolution
3960 * it's not important, as by the time that FWD type (reference type) will be
3961 * deduplicated all structs/unions will be deduped already anyway.
3962 *
3963 * Recording STRUCT/UNION mapping is purely a performance optimization and is
3964 * not required for correctness. It needs to be done carefully to ensure that
3965 * struct/union from candidate's type graph is not mapped into corresponding
3966 * struct/union from canonical type graph that itself hasn't been resolved into
3967 * canonical representative. The only guarantee we have is that canonical
3968 * struct/union was determined as canonical and that won't change. But any
3969 * types referenced through that struct/union fields could have been not yet
3970 * resolved, so in case like that it's too early to establish any kind of
3971 * correspondence between structs/unions.
3972 *
3973 * No canonical correspondence is derived for primitive types (they are already
3974 * deduplicated completely already anyway) or reference types (they rely on
3975 * stability of struct/union canonical relationship for equivalence checks).
3976 */
btf_dedup_merge_hypot_map(struct btf_dedup * d)3977 static void btf_dedup_merge_hypot_map(struct btf_dedup *d)
3978 {
3979 __u32 canon_type_id, targ_type_id;
3980 __u16 t_kind, c_kind;
3981 __u32 t_id, c_id;
3982 int i;
3983
3984 for (i = 0; i < d->hypot_cnt; i++) {
3985 canon_type_id = d->hypot_list[i];
3986 targ_type_id = d->hypot_map[canon_type_id];
3987 t_id = resolve_type_id(d, targ_type_id);
3988 c_id = resolve_type_id(d, canon_type_id);
3989 t_kind = btf_kind(btf__type_by_id(d->btf, t_id));
3990 c_kind = btf_kind(btf__type_by_id(d->btf, c_id));
3991 /*
3992 * Resolve FWD into STRUCT/UNION.
3993 * It's ok to resolve FWD into STRUCT/UNION that's not yet
3994 * mapped to canonical representative (as opposed to
3995 * STRUCT/UNION <--> STRUCT/UNION mapping logic below), because
3996 * eventually that struct is going to be mapped and all resolved
3997 * FWDs will automatically resolve to correct canonical
3998 * representative. This will happen before ref type deduping,
3999 * which critically depends on stability of these mapping. This
4000 * stability is not a requirement for STRUCT/UNION equivalence
4001 * checks, though.
4002 */
4003
4004 /* if it's the split BTF case, we still need to point base FWD
4005 * to STRUCT/UNION in a split BTF, because FWDs from split BTF
4006 * will be resolved against base FWD. If we don't point base
4007 * canonical FWD to the resolved STRUCT/UNION, then all the
4008 * FWDs in split BTF won't be correctly resolved to a proper
4009 * STRUCT/UNION.
4010 */
4011 if (t_kind != BTF_KIND_FWD && c_kind == BTF_KIND_FWD)
4012 d->map[c_id] = t_id;
4013
4014 /* if graph equivalence determined that we'd need to adjust
4015 * base canonical types, then we need to only point base FWDs
4016 * to STRUCTs/UNIONs and do no more modifications. For all
4017 * other purposes the type graphs were not equivalent.
4018 */
4019 if (d->hypot_adjust_canon)
4020 continue;
4021
4022 if (t_kind == BTF_KIND_FWD && c_kind != BTF_KIND_FWD)
4023 d->map[t_id] = c_id;
4024
4025 if ((t_kind == BTF_KIND_STRUCT || t_kind == BTF_KIND_UNION) &&
4026 c_kind != BTF_KIND_FWD &&
4027 is_type_mapped(d, c_id) &&
4028 !is_type_mapped(d, t_id)) {
4029 /*
4030 * as a perf optimization, we can map struct/union
4031 * that's part of type graph we just verified for
4032 * equivalence. We can do that for struct/union that has
4033 * canonical representative only, though.
4034 */
4035 d->map[t_id] = c_id;
4036 }
4037 }
4038 }
4039
4040 /*
4041 * Deduplicate struct/union types.
4042 *
4043 * For each struct/union type its type signature hash is calculated, taking
4044 * into account type's name, size, number, order and names of fields, but
4045 * ignoring type ID's referenced from fields, because they might not be deduped
4046 * completely until after reference types deduplication phase. This type hash
4047 * is used to iterate over all potential canonical types, sharing same hash.
4048 * For each canonical candidate we check whether type graphs that they form
4049 * (through referenced types in fields and so on) are equivalent using algorithm
4050 * implemented in `btf_dedup_is_equiv`. If such equivalence is found and
4051 * BTF_KIND_FWD resolution is allowed, then hypothetical mapping
4052 * (btf_dedup->hypot_map) produced by aforementioned type graph equivalence
4053 * algorithm is used to record FWD -> STRUCT/UNION mapping. It's also used to
4054 * potentially map other structs/unions to their canonical representatives,
4055 * if such relationship hasn't yet been established. This speeds up algorithm
4056 * by eliminating some of the duplicate work.
4057 *
4058 * If no matching canonical representative was found, struct/union is marked
4059 * as canonical for itself and is added into btf_dedup->dedup_table hash map
4060 * for further look ups.
4061 */
btf_dedup_struct_type(struct btf_dedup * d,__u32 type_id)4062 static int btf_dedup_struct_type(struct btf_dedup *d, __u32 type_id)
4063 {
4064 struct btf_type *cand_type, *t;
4065 struct hashmap_entry *hash_entry;
4066 /* if we don't find equivalent type, then we are canonical */
4067 __u32 new_id = type_id;
4068 __u16 kind;
4069 long h;
4070
4071 /* already deduped or is in process of deduping (loop detected) */
4072 if (d->map[type_id] <= BTF_MAX_NR_TYPES)
4073 return 0;
4074
4075 t = btf_type_by_id(d->btf, type_id);
4076 kind = btf_kind(t);
4077
4078 if (kind != BTF_KIND_STRUCT && kind != BTF_KIND_UNION)
4079 return 0;
4080
4081 h = btf_hash_struct(t);
4082 for_each_dedup_cand(d, hash_entry, h) {
4083 __u32 cand_id = (__u32)(long)hash_entry->value;
4084 int eq;
4085
4086 /*
4087 * Even though btf_dedup_is_equiv() checks for
4088 * btf_shallow_equal_struct() internally when checking two
4089 * structs (unions) for equivalence, we need to guard here
4090 * from picking matching FWD type as a dedup candidate.
4091 * This can happen due to hash collision. In such case just
4092 * relying on btf_dedup_is_equiv() would lead to potentially
4093 * creating a loop (FWD -> STRUCT and STRUCT -> FWD), because
4094 * FWD and compatible STRUCT/UNION are considered equivalent.
4095 */
4096 cand_type = btf_type_by_id(d->btf, cand_id);
4097 if (!btf_shallow_equal_struct(t, cand_type))
4098 continue;
4099
4100 btf_dedup_clear_hypot_map(d);
4101 eq = btf_dedup_is_equiv(d, type_id, cand_id);
4102 if (eq < 0)
4103 return eq;
4104 if (!eq)
4105 continue;
4106 btf_dedup_merge_hypot_map(d);
4107 if (d->hypot_adjust_canon) /* not really equivalent */
4108 continue;
4109 new_id = cand_id;
4110 break;
4111 }
4112
4113 d->map[type_id] = new_id;
4114 if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
4115 return -ENOMEM;
4116
4117 return 0;
4118 }
4119
btf_dedup_struct_types(struct btf_dedup * d)4120 static int btf_dedup_struct_types(struct btf_dedup *d)
4121 {
4122 int i, err;
4123
4124 for (i = 0; i < d->btf->nr_types; i++) {
4125 err = btf_dedup_struct_type(d, d->btf->start_id + i);
4126 if (err)
4127 return err;
4128 }
4129 return 0;
4130 }
4131
4132 /*
4133 * Deduplicate reference type.
4134 *
4135 * Once all primitive and struct/union types got deduplicated, we can easily
4136 * deduplicate all other (reference) BTF types. This is done in two steps:
4137 *
4138 * 1. Resolve all referenced type IDs into their canonical type IDs. This
4139 * resolution can be done either immediately for primitive or struct/union types
4140 * (because they were deduped in previous two phases) or recursively for
4141 * reference types. Recursion will always terminate at either primitive or
4142 * struct/union type, at which point we can "unwind" chain of reference types
4143 * one by one. There is no danger of encountering cycles because in C type
4144 * system the only way to form type cycle is through struct/union, so any chain
4145 * of reference types, even those taking part in a type cycle, will inevitably
4146 * reach struct/union at some point.
4147 *
4148 * 2. Once all referenced type IDs are resolved into canonical ones, BTF type
4149 * becomes "stable", in the sense that no further deduplication will cause
4150 * any changes to it. With that, it's now possible to calculate type's signature
4151 * hash (this time taking into account referenced type IDs) and loop over all
4152 * potential canonical representatives. If no match was found, current type
4153 * will become canonical representative of itself and will be added into
4154 * btf_dedup->dedup_table as another possible canonical representative.
4155 */
btf_dedup_ref_type(struct btf_dedup * d,__u32 type_id)4156 static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id)
4157 {
4158 struct hashmap_entry *hash_entry;
4159 __u32 new_id = type_id, cand_id;
4160 struct btf_type *t, *cand;
4161 /* if we don't find equivalent type, then we are representative type */
4162 int ref_type_id;
4163 long h;
4164
4165 if (d->map[type_id] == BTF_IN_PROGRESS_ID)
4166 return -ELOOP;
4167 if (d->map[type_id] <= BTF_MAX_NR_TYPES)
4168 return resolve_type_id(d, type_id);
4169
4170 t = btf_type_by_id(d->btf, type_id);
4171 d->map[type_id] = BTF_IN_PROGRESS_ID;
4172
4173 switch (btf_kind(t)) {
4174 case BTF_KIND_CONST:
4175 case BTF_KIND_VOLATILE:
4176 case BTF_KIND_RESTRICT:
4177 case BTF_KIND_PTR:
4178 case BTF_KIND_TYPEDEF:
4179 case BTF_KIND_FUNC:
4180 ref_type_id = btf_dedup_ref_type(d, t->type);
4181 if (ref_type_id < 0)
4182 return ref_type_id;
4183 t->type = ref_type_id;
4184
4185 h = btf_hash_common(t);
4186 for_each_dedup_cand(d, hash_entry, h) {
4187 cand_id = (__u32)(long)hash_entry->value;
4188 cand = btf_type_by_id(d->btf, cand_id);
4189 if (btf_equal_common(t, cand)) {
4190 new_id = cand_id;
4191 break;
4192 }
4193 }
4194 break;
4195
4196 case BTF_KIND_ARRAY: {
4197 struct btf_array *info = btf_array(t);
4198
4199 ref_type_id = btf_dedup_ref_type(d, info->type);
4200 if (ref_type_id < 0)
4201 return ref_type_id;
4202 info->type = ref_type_id;
4203
4204 ref_type_id = btf_dedup_ref_type(d, info->index_type);
4205 if (ref_type_id < 0)
4206 return ref_type_id;
4207 info->index_type = ref_type_id;
4208
4209 h = btf_hash_array(t);
4210 for_each_dedup_cand(d, hash_entry, h) {
4211 cand_id = (__u32)(long)hash_entry->value;
4212 cand = btf_type_by_id(d->btf, cand_id);
4213 if (btf_equal_array(t, cand)) {
4214 new_id = cand_id;
4215 break;
4216 }
4217 }
4218 break;
4219 }
4220
4221 case BTF_KIND_FUNC_PROTO: {
4222 struct btf_param *param;
4223 __u16 vlen;
4224 int i;
4225
4226 ref_type_id = btf_dedup_ref_type(d, t->type);
4227 if (ref_type_id < 0)
4228 return ref_type_id;
4229 t->type = ref_type_id;
4230
4231 vlen = btf_vlen(t);
4232 param = btf_params(t);
4233 for (i = 0; i < vlen; i++) {
4234 ref_type_id = btf_dedup_ref_type(d, param->type);
4235 if (ref_type_id < 0)
4236 return ref_type_id;
4237 param->type = ref_type_id;
4238 param++;
4239 }
4240
4241 h = btf_hash_fnproto(t);
4242 for_each_dedup_cand(d, hash_entry, h) {
4243 cand_id = (__u32)(long)hash_entry->value;
4244 cand = btf_type_by_id(d->btf, cand_id);
4245 if (btf_equal_fnproto(t, cand)) {
4246 new_id = cand_id;
4247 break;
4248 }
4249 }
4250 break;
4251 }
4252
4253 default:
4254 return -EINVAL;
4255 }
4256
4257 d->map[type_id] = new_id;
4258 if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
4259 return -ENOMEM;
4260
4261 return new_id;
4262 }
4263
btf_dedup_ref_types(struct btf_dedup * d)4264 static int btf_dedup_ref_types(struct btf_dedup *d)
4265 {
4266 int i, err;
4267
4268 for (i = 0; i < d->btf->nr_types; i++) {
4269 err = btf_dedup_ref_type(d, d->btf->start_id + i);
4270 if (err < 0)
4271 return err;
4272 }
4273 /* we won't need d->dedup_table anymore */
4274 hashmap__free(d->dedup_table);
4275 d->dedup_table = NULL;
4276 return 0;
4277 }
4278
4279 /*
4280 * Compact types.
4281 *
4282 * After we established for each type its corresponding canonical representative
4283 * type, we now can eliminate types that are not canonical and leave only
4284 * canonical ones layed out sequentially in memory by copying them over
4285 * duplicates. During compaction btf_dedup->hypot_map array is reused to store
4286 * a map from original type ID to a new compacted type ID, which will be used
4287 * during next phase to "fix up" type IDs, referenced from struct/union and
4288 * reference types.
4289 */
btf_dedup_compact_types(struct btf_dedup * d)4290 static int btf_dedup_compact_types(struct btf_dedup *d)
4291 {
4292 __u32 *new_offs;
4293 __u32 next_type_id = d->btf->start_id;
4294 const struct btf_type *t;
4295 void *p;
4296 int i, id, len;
4297
4298 /* we are going to reuse hypot_map to store compaction remapping */
4299 d->hypot_map[0] = 0;
4300 /* base BTF types are not renumbered */
4301 for (id = 1; id < d->btf->start_id; id++)
4302 d->hypot_map[id] = id;
4303 for (i = 0, id = d->btf->start_id; i < d->btf->nr_types; i++, id++)
4304 d->hypot_map[id] = BTF_UNPROCESSED_ID;
4305
4306 p = d->btf->types_data;
4307
4308 for (i = 0, id = d->btf->start_id; i < d->btf->nr_types; i++, id++) {
4309 if (d->map[id] != id)
4310 continue;
4311
4312 t = btf__type_by_id(d->btf, id);
4313 len = btf_type_size(t);
4314 if (len < 0)
4315 return len;
4316
4317 memmove(p, t, len);
4318 d->hypot_map[id] = next_type_id;
4319 d->btf->type_offs[next_type_id - d->btf->start_id] = p - d->btf->types_data;
4320 p += len;
4321 next_type_id++;
4322 }
4323
4324 /* shrink struct btf's internal types index and update btf_header */
4325 d->btf->nr_types = next_type_id - d->btf->start_id;
4326 d->btf->type_offs_cap = d->btf->nr_types;
4327 d->btf->hdr->type_len = p - d->btf->types_data;
4328 new_offs = libbpf_reallocarray(d->btf->type_offs, d->btf->type_offs_cap,
4329 sizeof(*new_offs));
4330 if (d->btf->type_offs_cap && !new_offs)
4331 return -ENOMEM;
4332 d->btf->type_offs = new_offs;
4333 d->btf->hdr->str_off = d->btf->hdr->type_len;
4334 d->btf->raw_size = d->btf->hdr->hdr_len + d->btf->hdr->type_len + d->btf->hdr->str_len;
4335 return 0;
4336 }
4337
4338 /*
4339 * Figure out final (deduplicated and compacted) type ID for provided original
4340 * `type_id` by first resolving it into corresponding canonical type ID and
4341 * then mapping it to a deduplicated type ID, stored in btf_dedup->hypot_map,
4342 * which is populated during compaction phase.
4343 */
btf_dedup_remap_type_id(__u32 * type_id,void * ctx)4344 static int btf_dedup_remap_type_id(__u32 *type_id, void *ctx)
4345 {
4346 struct btf_dedup *d = ctx;
4347 __u32 resolved_type_id, new_type_id;
4348
4349 resolved_type_id = resolve_type_id(d, *type_id);
4350 new_type_id = d->hypot_map[resolved_type_id];
4351 if (new_type_id > BTF_MAX_NR_TYPES)
4352 return -EINVAL;
4353
4354 *type_id = new_type_id;
4355 return 0;
4356 }
4357
4358 /*
4359 * Remap referenced type IDs into deduped type IDs.
4360 *
4361 * After BTF types are deduplicated and compacted, their final type IDs may
4362 * differ from original ones. The map from original to a corresponding
4363 * deduped type ID is stored in btf_dedup->hypot_map and is populated during
4364 * compaction phase. During remapping phase we are rewriting all type IDs
4365 * referenced from any BTF type (e.g., struct fields, func proto args, etc) to
4366 * their final deduped type IDs.
4367 */
btf_dedup_remap_types(struct btf_dedup * d)4368 static int btf_dedup_remap_types(struct btf_dedup *d)
4369 {
4370 int i, r;
4371
4372 for (i = 0; i < d->btf->nr_types; i++) {
4373 struct btf_type *t = btf_type_by_id(d->btf, d->btf->start_id + i);
4374
4375 r = btf_type_visit_type_ids(t, btf_dedup_remap_type_id, d);
4376 if (r)
4377 return r;
4378 }
4379
4380 if (!d->btf_ext)
4381 return 0;
4382
4383 r = btf_ext_visit_type_ids(d->btf_ext, btf_dedup_remap_type_id, d);
4384 if (r)
4385 return r;
4386
4387 return 0;
4388 }
4389
4390 /*
4391 * Probe few well-known locations for vmlinux kernel image and try to load BTF
4392 * data out of it to use for target BTF.
4393 */
libbpf_find_kernel_btf(void)4394 struct btf *libbpf_find_kernel_btf(void)
4395 {
4396 struct {
4397 const char *path_fmt;
4398 bool raw_btf;
4399 } locations[] = {
4400 /* try canonical vmlinux BTF through sysfs first */
4401 { "/sys/kernel/btf/vmlinux", true /* raw BTF */ },
4402 /* fall back to trying to find vmlinux ELF on disk otherwise */
4403 { "/boot/vmlinux-%1$s" },
4404 { "/lib/modules/%1$s/vmlinux-%1$s" },
4405 { "/lib/modules/%1$s/build/vmlinux" },
4406 { "/usr/lib/modules/%1$s/kernel/vmlinux" },
4407 { "/usr/lib/debug/boot/vmlinux-%1$s" },
4408 { "/usr/lib/debug/boot/vmlinux-%1$s.debug" },
4409 { "/usr/lib/debug/lib/modules/%1$s/vmlinux" },
4410 };
4411 char path[PATH_MAX + 1];
4412 struct utsname buf;
4413 struct btf *btf;
4414 int i;
4415
4416 uname(&buf);
4417
4418 for (i = 0; i < ARRAY_SIZE(locations); i++) {
4419 snprintf(path, PATH_MAX, locations[i].path_fmt, buf.release);
4420
4421 if (access(path, R_OK))
4422 continue;
4423
4424 if (locations[i].raw_btf)
4425 btf = btf__parse_raw(path);
4426 else
4427 btf = btf__parse_elf(path, NULL);
4428
4429 pr_debug("loading kernel BTF '%s': %ld\n",
4430 path, IS_ERR(btf) ? PTR_ERR(btf) : 0);
4431 if (IS_ERR(btf))
4432 continue;
4433
4434 return btf;
4435 }
4436
4437 pr_warn("failed to find valid kernel BTF\n");
4438 return ERR_PTR(-ESRCH);
4439 }
4440
btf_type_visit_type_ids(struct btf_type * t,type_id_visit_fn visit,void * ctx)4441 int btf_type_visit_type_ids(struct btf_type *t, type_id_visit_fn visit, void *ctx)
4442 {
4443 int i, n, err;
4444
4445 switch (btf_kind(t)) {
4446 case BTF_KIND_INT:
4447 case BTF_KIND_FLOAT:
4448 case BTF_KIND_ENUM:
4449 return 0;
4450
4451 case BTF_KIND_FWD:
4452 case BTF_KIND_CONST:
4453 case BTF_KIND_VOLATILE:
4454 case BTF_KIND_RESTRICT:
4455 case BTF_KIND_PTR:
4456 case BTF_KIND_TYPEDEF:
4457 case BTF_KIND_FUNC:
4458 case BTF_KIND_VAR:
4459 return visit(&t->type, ctx);
4460
4461 case BTF_KIND_ARRAY: {
4462 struct btf_array *a = btf_array(t);
4463
4464 err = visit(&a->type, ctx);
4465 err = err ?: visit(&a->index_type, ctx);
4466 return err;
4467 }
4468
4469 case BTF_KIND_STRUCT:
4470 case BTF_KIND_UNION: {
4471 struct btf_member *m = btf_members(t);
4472
4473 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
4474 err = visit(&m->type, ctx);
4475 if (err)
4476 return err;
4477 }
4478 return 0;
4479 }
4480
4481 case BTF_KIND_FUNC_PROTO: {
4482 struct btf_param *m = btf_params(t);
4483
4484 err = visit(&t->type, ctx);
4485 if (err)
4486 return err;
4487 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
4488 err = visit(&m->type, ctx);
4489 if (err)
4490 return err;
4491 }
4492 return 0;
4493 }
4494
4495 case BTF_KIND_DATASEC: {
4496 struct btf_var_secinfo *m = btf_var_secinfos(t);
4497
4498 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
4499 err = visit(&m->type, ctx);
4500 if (err)
4501 return err;
4502 }
4503 return 0;
4504 }
4505
4506 default:
4507 return -EINVAL;
4508 }
4509 }
4510
btf_type_visit_str_offs(struct btf_type * t,str_off_visit_fn visit,void * ctx)4511 int btf_type_visit_str_offs(struct btf_type *t, str_off_visit_fn visit, void *ctx)
4512 {
4513 int i, n, err;
4514
4515 err = visit(&t->name_off, ctx);
4516 if (err)
4517 return err;
4518
4519 switch (btf_kind(t)) {
4520 case BTF_KIND_STRUCT:
4521 case BTF_KIND_UNION: {
4522 struct btf_member *m = btf_members(t);
4523
4524 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
4525 err = visit(&m->name_off, ctx);
4526 if (err)
4527 return err;
4528 }
4529 break;
4530 }
4531 case BTF_KIND_ENUM: {
4532 struct btf_enum *m = btf_enum(t);
4533
4534 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
4535 err = visit(&m->name_off, ctx);
4536 if (err)
4537 return err;
4538 }
4539 break;
4540 }
4541 case BTF_KIND_FUNC_PROTO: {
4542 struct btf_param *m = btf_params(t);
4543
4544 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
4545 err = visit(&m->name_off, ctx);
4546 if (err)
4547 return err;
4548 }
4549 break;
4550 }
4551 default:
4552 break;
4553 }
4554
4555 return 0;
4556 }
4557
btf_ext_visit_type_ids(struct btf_ext * btf_ext,type_id_visit_fn visit,void * ctx)4558 int btf_ext_visit_type_ids(struct btf_ext *btf_ext, type_id_visit_fn visit, void *ctx)
4559 {
4560 const struct btf_ext_info *seg;
4561 struct btf_ext_info_sec *sec;
4562 int i, err;
4563
4564 seg = &btf_ext->func_info;
4565 for_each_btf_ext_sec(seg, sec) {
4566 struct bpf_func_info_min *rec;
4567
4568 for_each_btf_ext_rec(seg, sec, i, rec) {
4569 err = visit(&rec->type_id, ctx);
4570 if (err < 0)
4571 return err;
4572 }
4573 }
4574
4575 seg = &btf_ext->core_relo_info;
4576 for_each_btf_ext_sec(seg, sec) {
4577 struct bpf_core_relo *rec;
4578
4579 for_each_btf_ext_rec(seg, sec, i, rec) {
4580 err = visit(&rec->type_id, ctx);
4581 if (err < 0)
4582 return err;
4583 }
4584 }
4585
4586 return 0;
4587 }
4588
btf_ext_visit_str_offs(struct btf_ext * btf_ext,str_off_visit_fn visit,void * ctx)4589 int btf_ext_visit_str_offs(struct btf_ext *btf_ext, str_off_visit_fn visit, void *ctx)
4590 {
4591 const struct btf_ext_info *seg;
4592 struct btf_ext_info_sec *sec;
4593 int i, err;
4594
4595 seg = &btf_ext->func_info;
4596 for_each_btf_ext_sec(seg, sec) {
4597 err = visit(&sec->sec_name_off, ctx);
4598 if (err)
4599 return err;
4600 }
4601
4602 seg = &btf_ext->line_info;
4603 for_each_btf_ext_sec(seg, sec) {
4604 struct bpf_line_info_min *rec;
4605
4606 err = visit(&sec->sec_name_off, ctx);
4607 if (err)
4608 return err;
4609
4610 for_each_btf_ext_rec(seg, sec, i, rec) {
4611 err = visit(&rec->file_name_off, ctx);
4612 if (err)
4613 return err;
4614 err = visit(&rec->line_off, ctx);
4615 if (err)
4616 return err;
4617 }
4618 }
4619
4620 seg = &btf_ext->core_relo_info;
4621 for_each_btf_ext_sec(seg, sec) {
4622 struct bpf_core_relo *rec;
4623
4624 err = visit(&sec->sec_name_off, ctx);
4625 if (err)
4626 return err;
4627
4628 for_each_btf_ext_rec(seg, sec, i, rec) {
4629 err = visit(&rec->access_str_off, ctx);
4630 if (err)
4631 return err;
4632 }
4633 }
4634
4635 return 0;
4636 }
4637